Climate
Your first step in determining a region’s baseline weather is to decide upon the region’s climate. Climate is split up into one of three categories: cold, temperate and tropical. These types correspond to the three climate categories used in monster entries (note that a fourth category, extraplanar, is not a factor in determining weather for Material Plane worlds).
The baseline temperature range for each climate category is given below, and is further refined in Temperature.
Polar: A polar climate is found in the extreme northern or southern regions of the world at latitudes greater than 66 degrees. In these polar regions, temperatures often remain below freezing throughout the majority of the year. The baseline temperature in this climate ranges from -20º C in the winter, to -10º C in the spring and fall months, and up to 0º C in the summer. Because cold air tends to be drier than warm air, reduce the frequency and intensity of precipitation by one step in cold climates.
Boreal: A boreal climate is found adjacent to polar climates at latitudes greater that 55 degrees. These subpolar regions are characterised by long, usually very cold winters, and short, cool to mild summers. The baseline temperature in this climate ranges from -20º C in the winter, to -5º C in the spring and fall months, and up to 10º C in the summer. Because cold air tends to be drier than warm air, reduce the frequency and intensity of precipitation by one step in cold climates.
Continental: A continental climate is found adjacent towards the equator to boreal climates at latitudes greater that 45 degrees. The baseline temperature in this climate is cold, ranging from -10º C in the winter, to 5º C in the spring and fall months, and up to 20º C in the summer. Precipitation frequency is not altered as a result of a continental climate, but it can still be altered as a result of other factors such as the elevation or season (see below).
Temperate: A temperate climate is found adjacent towards the equator to continental climates at latitudes greater that 35 degrees. The baseline temperature in this climate ranges from 0º C in winter, to 15º C in spring and fall, and all the way up to 25º F in summer. Precipitation frequency is not altered as a result of a temperate climate, but it can still be altered as a result of other factors such as the elevation or season (see below).
Subtropical: A subtropical climate is found adjacent to tropical climates at latitudes greater that 25 degrees. The baseline temperature in this climate ranges from 10º C in winter, to 20º C in spring and fall, and all the way up to 30º F in summer. Because warm, humid air produces a great deal of precipitation, increase the frequency and intensity of precipitation by one step in this climate.
Tropical: The tropics exist to either side of the world’s equator, extending north and south for about 25 degrees of latitude in either direction. Tropical regions tend to be warm and humid, with a baseline temperature ranging from 20º C in winter, to 25º C in spring and fall, and up to 35º C in summer. Because warm, humid air produces a great deal of precipitation, increase the frequency and intensity of precipitation by one step in this climate.
Table: Climate Baselines
| Climate | Winter Temp. | Spring Temp. | Summer Temp. | Fall Temp. | Precipitation Adjustment |
|---|---|---|---|---|---|
| Polar | -20º C | -10º C | 0º C | -10º C | Decrease frequency and intensity by one step |
| Boreal | -20 C | -5º C | 10º C | -5º C | Decrease frequency and intensity by one step |
| Continental | -10º C | 5º C | 20º C | 5º C | — |
| Temperate | 0º C | 15º C | 25º C | 15º C | — |
| Subtropical | 10º C | 20º C | 30º C | 20º C | Increase frequency and intensity by one step |
| Tropical | 20º C | 25º C | 35º C | 25º C | Increase frequency and intensity by one step |
Table: Polar and Boreal Region Temperature Variations
| d% | Variation | Duration |
|---|---|---|
| 1–20 | –1d20° C | 1d4 days |
| 21–40 | –1d10° C | 1d6+1 days |
| 41–60 | –1d6° C | 1d6+2 days |
| 61–80 | No variation | 1d6+2 days |
| 81–95 | +1d6° C | 1d6+1 days |
| 96–99 | +1d10° C | 1d4 days |
| 100 | +1d20° C | 1d2 days |
Table: Continental and Temperate Region Temperature Variations
| d% | Variation | Duration |
|---|---|---|
| 1–5 | –1d20° C | 1d2 days |
| 6–15 | –1d10° C | 1d4 days |
| 16–35 | –1d6° C | 1d4+1 days |
| 36–65 | No variation | 1d6+1 days |
| 66–85 | +1d6° C | 1d4+1 days |
| 86–95 | +1d10° C | 1d4 days |
| 96–100 | +1d20° C | 1d2 days |
Table: Subtropical and Tropical Region Temperature Variations
| d% | Variation | Duration |
|---|---|---|
| 1–10 | –1d10° C | 1d2 days |
| 11–25 | –1d6° C | 1d2 days |
| 26–55 | No variation | 1d4 days |
| 56–85 | +1d6° C | 1d4 days |
| 86–100 | +1d10° C | 1d2 days |
Cloud Cover
You can roll on Table: Cloud Cover to determine the cloud cover for the day. Light and medium cloud cover mainly serve as thematic elements. Overcast conditions grant concealment for creatures flying at high altitudes. Overcast conditions without precipitation increase the temperature in fall and winter by 5° C and decrease the temperature in spring and summer by the same amount. If precipitation occurs, the cloud cover functions as overcast.
Table: Cloud Cover
| d% | Cloud Cover |
|---|---|
| 1–50 | None |
| 51–70 | Light clouds |
| 71–85 | Medium clouds |
| 86–100 | Overcast |
Elevation
While the climate sets baselines for temperatures, elevation plays a key factor as well. Elevation can affect the baseline temperature, and it sets the baseline intensity of precipitation in the region, as explained below and displayed in Table: Elevation Baselines.
Sea Level: Temperatures in sea-level and coastal regions are 5º warmer. Sea-level regions also tend to have more precipitation than areas of higher elevation, so the baseline precipitation intensity in a sea-level region is heavy.
Lowland: Lowlands are areas of low elevation not near the coast, generally at an elevation of 1,000 to 5,000 feet. This elevation range does not alter baseline temperatures. The baseline precipitation intensity in lowlands is medium.
Highland: Highlands include regions with elevations above 5,000 feet. Decrease baseline temperatures in highlands by 5º (although in particularly arid and flat regions, you should instead increase the baseline temperature by 5º, while in particularly high-altitude regions such as significant mountain ranges, you should instead decrease the baseline temperature by 10º). The frequency of precipitation is decreased by one step, and baseline precipitation intensity is medium.
Precipitation
Precipitation Frequency
Precipitation frequency is organized into five levels: drought, rare, intermittent, common, and constant. A region’s baseline precipitation frequency is set by the season, but it can be modified by the climate and other factors (for example, see the Deserts sidebar). A precipitation frequency can’t be reduced lower than drought or increased higher than constant. Check each day to determine whether precipitation occurs for that day; the percentage chance of precipitation occurring is summarized on Table: Daily Precipitation Chances.
Deserts: Deserts are found in places where the weather must pass over mountains, causing a rain shadow, and in very cold environments. The baseline precipitation frequency in a desert is usually drought, but can be rare for a few weeks per year.
Table: Daily Precipitation Chances
| Frequency | Chance of Precipitation |
|---|---|
| Drought | 5% (decrease precipitation intensity by two steps) |
| Rare | 15% |
| Intermittent | 30% |
| Common | 60% |
| Constant | 95% |
Table: Elevation Baselines
| Elevation | Altitude Range | Baseline Temp. | Adjust. Baseline Precipitation Intensity |
|---|---|---|---|
| Sea level | Below 1,000 ft. | +5º C | Heavy |
| Lowland | 1,000 ft. to 5,000 ft. | — | Medium |
| Highland | Above 5,000 ft. | –5º C | Medium (decrease precipitation frequency by one step) |
Table: Seasonal Baselines
| Season | Cold or Temperate Climate Precip. Frequency | Tropical Climate Precip. Frequency |
|---|---|---|
| Spring | Intermittent | Common |
| Summer | Common | Intermittent |
| Fall | Intermittent | Common |
| Winter | Rare | Rare |
Precipitation Intensity
The baseline precipitation intensity is dependent on the elevation and can be modified by the climate. Intensity has four categories. Light precipitation is the lowest level of intensity and generally consists of fog, a faint drizzle of rain or a few isolated flakes of snow. Medium precipitation represents a noticeable but not distracting fall of rain or snow. Heavy precipitation typically consists of a driving rainstorm or significant snowfall. Torrential precipitation is the highest level of intensity and consists of a deluge of rain or snow with conditions that can approach whiteout levels. Precipitation intensity can never be reduced below light or increased above torrential.
Once you establish the intensity and the temperature, you’ll determine how the precipitation manifests.
Precipitation Form
Precipitation can result in more than just rain. Depending upon the intensity and temperature, precipitation can range from a light fog or a faint drizzle of rain to a blizzard or thunderstorm. Once you know precipitation of a specific intensity is occurring, set the time of day the precipitation event occurs by rolling 1d12 to find the starting hour of the day and 1d6 to determine whether the hour is a.m. or p.m. (1–3 = a.m., 4–6 = p.m.).
Next, use the appropriate table below for the baseline precipitation intensity and whether the temperature is above or below freezing (0° C) to generate the specific type of precipitation and its duration. (Remember that the temperature is lower at night!) See the Cloud Cover section for the effects of precipitation on visibility for flying creatures.
Table: Light Unfrozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–20 | Light fog | 1d8 hours |
| 21–40 | Medium fog | 1d6 hours |
| 41–50 | Drizzle | 1d4 hours |
| 51–75 | Drizzle | 2d12 hours |
| 76–90 | Light rain | 1d4 hours |
| 91–100 | Light rain (sleet if below 5° C) | 1 hour |
Table: Light Frozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–20 | Light fog | 1d6 hours |
| 21–40 | Light fog | 1d8 hours |
| 41–50 | Medium fog | 1d4 hours |
| 51–60 | Light snow | 1 hour |
| 61–75 | Light snow | 1d4 hours |
| 76–100 | Light snow | 2d12 hours |
Table: Medium Unfrozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 01–10 | Medium fog | 1d8 hours |
| 11–20 | Medium fog | 1d12 hours |
| 21–30 | Heavy fog | 1d4 hours |
| 31–35 | Rain | 1d4 hours |
| 36–70 | Rain | 1d8 hours |
| 71–90 | Rain | 2d12 hours |
| 91–100 | Rain | (sleet if below 5° c) 1d4 hours |
Table: Medium Frozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–10 | Medium fog | 1d6 hours |
| 11–20 | Medium fog | 1d8 hours |
| 21–30 | Heavy fog | 1d4 hours |
| 31–50 | Medium snow | 1d4 hours |
| 51–90 | Medium snow | 1d8 hours |
| 91–100 | Medium snow | 2d12 hours |
Table: Heavy Unfrozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–10 | Heavy fog | 1d8 hours |
| 11–20 | Heavy fog | 2d6 hours |
| 21–50 | Heavy rain | 1d12 hours |
| 51–70 | Heavy rain | 2d12 hours |
| 71–85 | Heavy rain (sleet if below 5° C) | 1d8 hours |
| 86–90 | Thunderstorm | 1 hour |
| 91–100 | Thunderstorm | 1d3 hours |
Table: Heavy Frozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–10 | Medium fog | 1d8 hours |
| 11–20 | Heavy fog | 2d6 hours |
| 21–60 | Light snow | 2d12 hours |
| 61–90 | Medium snow | 1d8 hours |
| 91–100 | Heavy snow | 1d6 hours |
Table: Torrential Unfrozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–5 | Heavy fog | 1d8 hours |
| 6–10 | Heavy fog | 2d6 hours |
| 11–30 | Heavy rain | 2d6 hours |
| 31–60 | Heavy rain | 2d12 hours |
| 61–80 | Heavy rain (sleet if below 5° C) | 2d6 hours |
| 81–95 | Thunderstorm | 1d3 hours |
| 96–100 | Thunderstorm | 1d6 hours |
Table: Torrential Frozen Precipitation
| d% | Precipitation | Duration |
|---|---|---|
| 1–5 | Heavy fog | 1d8 hours |
| 6–10 | Heavy fog | 2d6 hours |
| 11–50 | Heavy snow | 1d4 hours |
| 51–90 | Heavy snow | 1d8 hours |
| 91–100 | Heavy snow | 2d12 hours |
Drizzle: Drizzle reduces visibility to three-quarters of the normal range, imposing a –2 penalty on Perception checks. It automatically extinguishes tiny unprotected flames (candles and the like, but not torches).
Fog, Heavy: Heavy fog obscures all vision beyond 5 feet, including darkvision. Creatures 5 feet away have concealment. Heavy fog typically occurs early in the day, late in the day, or sometimes at night, but the heat of the midday usually burns it away. Heavy fog occurs only when there is no or light wind.
Fog, Light: Light fog reduces visibility to three-quarters of the normal ranges, resulting in a –2 penalty on Perception checks and a –2 penalty on ranged attacks. Light fog typically occurs early in the day, late in the day, or sometimes at night, but the heat of the midday usually burns it away. Light fog occurs only when there is no or light wind.
Fog, Medium: Medium fog reduces visibility ranges by half, resulting in a –4 penalty on Perception checks and a –4 penalty on ranged attacks. Medium fog typically occurs early in the day, late in the day, or sometimes at night, but the heat of the midday usually burns it away. Medium fog occurs only when there is no or light wind.
Rain: Rain reduces visibility ranges by half, resulting in a –4 penalty on Perception checks. Rain automatically extinguishes unprotected flames (candles, torches, and the like) and imposes a –4 penalty on ranged attacks.
Rain, Heavy: Heavy rain reduces visibility to one-quarter of the normal range, resulting in a –6 penalty on Perception checks. Heavy rain automatically extinguishes unprotected flames and imposes a –6 penalty on ranged attacks.
Sleet: Essentially frozen rain, sleet has the same effect as light snow, but any accumulation typically doesn’t last longer than 1–2 hours after the storm.
Snow, Heavy: Heavy snow reduces visibility ranges to one-quarter of the normal range, resulting in a –6 penalty on Perception checks. It extinguishes unprotected flames and imposes a –6 penalty on ranged attacks. Heavy snow impedes movement even before it begins to stick. Moving into a square during a heavy snowstorm requires 1 extra 5-foot square of movement (this stacks with difficult terrain). Every hour of heavy snow leaves 1d4 inches of snow on the ground. As long as at least 2 inches of snow remain on the ground, the requirement of an extra square of movement to enter a square of snow persists. If at least 1 foot of snow remains on the ground, 2 extra squares of movement are required to enter a snow-filled square instead. A heavy snowstorm has a 10% chance of generating thundersnow and has a 40% chance of becoming a blizzard if the wind speed is severe or stronger.
Snow, Light: Light snow reduces visibility to three-quarters of the normal range, resulting in a –2 penalty on Perception checks. Light snow has a 75% chance each hour of extinguishing unprotected flames and imposes a –2 penalty on ranged attacks. Light snow does not impede movement unless it continues for 2 or more hours, at which point moving into a square of such snow requires 1 extra 5-foot square of movement (this stacks with difficult terrain). Every 2 hours of light snow leaves 1 inch of snow on the ground. As long as at least 2 inches of snow remain on the ground, the requirement of an extra square of movement to enter a square of snow persists. If at least 1 foot of snow remains on the ground, entering a snow-filled square instead requires 2 extra squares of movement.
Snow, Medium: Medium snow reduces visibility ranges by half, resulting in a –4 penalty on Perception checks. Medium snow extinguishes unprotected flames and imposes a –4 penalty on ranged attacks. Medium snow does not impede movement unless it continues for 1 hour, at which point moving into a square of such snow requires 1 extra 5-foot square of movement (this stacks with difficult terrain). Every hour of medium snow leaves 1 inch of snow on the ground. As long as at least 2 inches of snow remain on the ground, the requirement of an extra square of movement to enter a square of snow persists. If at least 1 foot of snow remains on the ground, entering a snow-filled square instead requires 2 extra squares of movement.
Thunderstorm: Thunderstorms feature powerful winds and heavy rain (see above). To determine the type of wind associated with the thunderstorm, roll on Table: Thunderstorm Winds.
Table: Thunderstorm Winds
| d% | Thunderstorm Wind Strength |
|---|---|
| 1–50 | Strong winds |
| 51–90 | Severe winds |
| 91–100 | Windstorm |
In addition, there is a 40% chance that a thunderstorm features hail either up to an hour before or during the storm. An even greater danger presented by a thunderstorm is the lightning that occurs during the storm. These electrical discharges, generated by the roiling clouds, can pose a hazard to creatures that do not have proper shelters, especially creatures clad in metal armor. Every 10 minutes during a thunderstorm, a bolt of lightning strikes an unsheltered creature at random (though this can strike wildlife as easily as PCs). A creature struck by this lightning must succeed a DC 18 Reflex saving throw or take 10d8 points of electricity damage (a successful saving throw halves the damage). Creatures in metal armor take a –4 penalty on the Reflex saving throw.
There is a 10% chance that a thunderstorm with winds of windstorm strength also generates a tornado, while thunderstorms with windstorm-strength winds in temperatures higher than 85° F also have a 20% chance of being a precursor to a hurricane. There is a 20% chance that a thunderstorm of any strength in the desert also generates a haboob.
Season
A year has four seasons—spring, summer, fall, and winter—each of which lasts about 3 months. Season plays an important part in dictating a region’s baseline temperature (as noted in each climate and in Table 4–14). It also dictates the baseline precipitation frequency in a region before applying adjustments due to climate or elevation. In most regions with cold and temperate climates, precipitation frequency is intermittent during spring and fall, common during the summer, and rare during the winter. In most regions with tropical climates, precipitation frequency is common during spring and fall, intermittent during the summer, and rare during the winter.
On worlds with a tilt in their axis, the seasons are typically reversed between northern and southern hemispheres. While it is the height of summer in the north, the areas south of the equator are in the depths of winter.
Severe Events
On rare occasions, weather can produce truly dramatic and dangerous events. The following severe effects are sometimes generated by extreme precipitation. For instance, thunderstorms can create or be a harbinger for haboobs, hail, tornados, wildfires, or even hurricanes. At other times, certain types of precipitation combined with higher wind strengths can generate these severe events.
Blizzard
A combination of severe or stronger winds with heavy snow can create blizzard conditions. Blizzards reduce range of vision to no more than 20 feet, and even then, creatures takes a –8 penalty on Perception checks within that range. In a blizzard, the snowfall increases to 4 inches of snow each hour, and travel in more than 3 feet of snow is usually impossible without snowshoes or an ability such as waterwalk. Furthermore, the high winds make it feel (and affect living creatures) as if the temperature were 20° F colder. There is a 20% chance that a blizzard lasts for 2d12 hours instead of the normal duration for heavy snow.
Haboob
A haboob is a sandstorm created by a thunderstorm. See Sandstorm below for its effects.
Hail
Hail typically occurs just before or during a thunderstorm. Hail does not reduce visibility, but the sound of falling hail imposes a –4 penalty on sound-based Perception checks. Rarely (5% chance), hail pellets can become large enough to deal 1d4 points of lethal damage per minute to creatures and objects out in the open.
Hurricane
Hurricanes are incredibly massive storms featuring heavy rain and a wind strength greater than that of the most powerful windstorm. With winds of 75–174 miles per hour, a hurricane renders ranged attacks impossible, and siege weapons take a –8 penalty on attack rolls. Large or smaller creatures must succeed at a DC 15 Strength check or they are unable to move forward against the strength of the wind. Medium or smaller creatures on the ground must succeed at a DC 15 Strength check or they are knocked prone and roll 1d6x10 feet, taking 1d6 points of nonlethal damage per 10 feet. Flying creatures must succeed at a DC 25 Fly check or they are blown back 2d8×10 feet and take 4d6 points of nonlethal damage due to battering and buffeting. Hurricanes also usually cause flooding. It’s nearly impossible to journey out into a hurricane unscathed.
Sandstorm
Sandstorms occur when severe or greater winds kick up sand and debris in a desert or similarly arid environment. Sandstorms reduce visibility to 1d10×10 feet, and those within them take a –6 penalty on Perception checks. Sandstorms deal 1d3 points of nonlethal damage per hour to creatures caught in the open.
Thundersnow
High winds in a snowstorm can create the rare phenomena known as thundersnow. Lighting strikes are less common in thundersnow, but just as deadly. Every hour during the storm, a bolt of lightning strikes an unsheltered creature at random (though this can strike wildlife as easily as PCs). A creature struck by this lightning must succeed a DC 18 Reflex saving throw or take 10d8 points of electricity damage (a successful saving throw halves the damage). Creatures in metal armor take a –4 penalty on the Reflex saving throw.
Tornado
With winds with speeds of 174–300 miles per hour, tornados are deadly terrors. The smallest tornados occupy a 20-foot-radius burst, with winds of windstorm strength swirling up to 100 feet beyond that burst. The largest tornados can be 100-foot-radius bursts, with a windstorm whose radius extends 500 feet beyond that burst. Ranged attacks, including normal, siege, and even those produced by evocation spells, are impossible in the core burst of a tornado. Huge or smaller creatures must succeed a DC 20 Strength check or be sucked up by the funnel of the tornado; this deals 8d8 points of bludgeoning, piercing, and slashing lethal damage to the creatures. This damage ignores all but DR/epic, DR/—, and hardness. Once it deals this damage, the tornado flings the creature it has sucked up 1d20×10 feet up and away from the tornado, dealing 1d6 points of falling damage per 10 feet that the creature is flung. Gargantuan and larger creatures take the 8d8 points of damage but are not moved by the tornado. A tornado moves at a speed of 40 feet, though the direction it moves is entirely unpredictable—you can determine the direction randomly each round. Tornados typically last for 3d6 minutes, but some can swirl for up to an hour. While most tornados are created by thunderstorms, some smaller tornados (typically with a 5- to 10-foot-burst radius, with no outer radius) can be created in areas of wildfire (firenados), snow (snownados), or sand (dust devils). They deal a similar amount of damage, but firenados deal fire damage, snownados deal cold damage, and dust devils deal bludgeoning damage only, and these types of tornados do not fling their targets.
Wildfire
While wildfires can be sparked a number of ways, for these rules, they are usually created by a lightning strike in a particularly dry area of forest or other vegetation. Use the rules for forest fires, but add a 10% chance of the fire producing 1d6 firenados (see Tornado above).
Temperature
Temperature Variations
Weather is constantly changing, and a significant aspect of that change is the temperature. For the purposes of this system, it’s easiest to assume that the daily temperature remains relatively static during daylight hours and then drops by 1d6+4 degrees during the night.
Cold
Cold and exposure can deal lethal cold damage to the victim. A character cannot recover from the damage dealt by a cold environment until she gets out of the cold and warms up again. A creature's cold resistance (if any) reduces the amount of cold damage, and creatures immune to cold are unaffected. Characters wearing a cold weather outfit gain a +5 bonus on Fortitude saving throws against exposure to cold weather.
A character who takes any cold damage from cold or exposure is beset by frostbite or hypothermia (treat her as fatigued). These penalties end when the character recovers the cold damage she took from the cold and exposure. If you take damage from cold or exposure while fatigued, you become exhausted.
- Cold weather (below 40°F/5°C) forces unprotected characters to make a Fortitude save each hour (DC 15, +1 per previous check) or take 1d4-1 cold damage. A character who has the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the skill description).
- Severe cold (below 0°F/-20°C) forces unprotected characters to make a Fortitude save once every hour (DC 20, +1 per previous check), taking 1d6+1 cold damage on each failed save. A character who has the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well. Characters wearing a cold weather outfit only need check once per four hours for cold and exposure damage.
- Extreme cold (below -20°F/-30°C) deals 6d6 cold damage per hour to unprotected characters. A character can make a Fortitude save (DC 25, +1 per previous check) to halve damage. Wearing a cold weather outfit reduces the damage to half on a failed save, and to a quarter on a successful save.
Heat
Heat deals fire damage that cannot be recovered from until the character gets cooled off (reaches shade, survives until nightfall, gets doused in water, is targeted by endure elements, and so forth). A creature's fire resistance (if any) reduces the damage, and creatures immune to fire are unaffected. Characters wearing a hot weather outfit gain a +2 bonus on Fortitude saving throws against exposure to hot temperatures. This does not stack with any bonuses gained from the Survival skill.
A character who takes any fire damage from heat exposure now suffers from heatstroke and is fatigued. These penalties end when the character recovers from the fire damage she took from the heat. If you take damage from heat or exposure while fatigued, you become exhausted.
- Very hot conditions (above 90°F/30°C) force characters to make a Fortitude saving throw each hour (DC 15, +1 for each previous check) or take 1d4 fire damage. Characters wearing heavy clothing or armor of any sort take a disadvantage on their saves. A character with the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the skill description).
- Severe heat (above 110°F/45°C) forces a character to make a Fortitude save once every hour (DC 20, +1 for each previous check) or take 1d6+1 points of fire damage. Characters wearing heavy clothing or medium or heavy armor of any sort take a disadvantage on their saves. A character with the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the Survival skill in Using Skills).
- Extreme heat (air temperature over 140°F/60°C, fire, boiling water, lava) deals 6d6 fire damage per hour. A character can make a Fortitude save (DC 25, +1 per previous check) to reduce the damage by half. Those wearing heavy clothing or any sort of armor take a disadvantage on their saves.
Wind
Once you’ve generated the day’s precipitation, you’ll need to establish the wind strength unless the precipitation indicates otherwise. For example, on foggy days, no significant wind occurs, while thunderstorms have their own rules for determining wind strength. To set the wind strength for the day, roll d% and consult the table above.
The following describes the categories listed in Table 4–28: Wind Strength.
Wind Strength: This is the category of the wind strength.
Wind Speed: This is the range of wind speeds that occur. Wind speed typically fluctuates between these values through the period of the day, and for moderate or higher wind strength, there are periods in the day when the wind speed dips below the listed range.
Ranged Weapon Penalty/Siege Weapon Penalty: These are the penalties that characters take when firing ranged weapons and siege weapons in wind of the listed strength. In windstorm-strength wind, normal ranged weapon attacks (either projectile or thrown) are impossible. This includes ranged attacks made via spells of the conjuration school, but it does not include evocation ranged attacks. Siege weapons include all weapons of that type and boulders thrown by giants and other creatures with the rock throwing special attack.
Check Size: Creatures of the listed size or smaller are unable to move forward against the force of the wind unless they succeed at a DC 10 Strength check (on the ground) or a DC 20 Fly check if airborne.
Blown Away Size: Creatures of the listed size on the ground are knocked prone, roll 1d4×10 feet, and take 2d6 points of nonlethal damage, unless they succeed on a DC 15 Strength check. Flying creatures of the listed size are blown back 2d6×10 feet and take 2d6 points of nonlethal damage due to battering and buffeting, unless they succeed at a DC 25 Fly check.
Skill Penalty: This is the penalty for skill checks that can be affected by the wind. These penalties always apply on Fly checks and sound-based Perception checks, but GMs may also wish to apply them on Acrobatics checks, Climb checks, and any other ability or skill checks that could be adversely affected by winds.
Table: Wind Strength
| d% | Wind Strength | Wind Speed | Ranged Weapon Penalty/ Siege Weapon Penalty |
Check Size | Blown Away Size | Skill Penalty |
|---|---|---|---|---|---|---|
| 1–50 | Light | 0–10 mph | —/— | — | — | — |
| 51–80 | Moderate | 11–20 mph | —/— | — | — | — |
| 81–90 | Strong | 21–30 mph | –2/— | Tiny | — | –2 |
| 91–95 | Severe | 31–50 mph | –4/— | Small | Tiny | –4 |
| 96–100 | Windstorm | 51+ mph | Impossible/–4 | Medium | Small | –8 |