Weather

Weather can play an important role in an adventure.

Table 13–9 can be used as a simple local weather table. Terms on that table are defined as follows.

Table 13–9: Random Weather

d%	Weather	Cold Climate	Temperate Climate¹	Desert
01–70	Normal weather	Cold, calm	Normal for season²	Hot, calm
71–80	Abnormal weather	Heat wave (01–30) or cold snap (31–100)	Heat wave (01–50) or cold snap (51–100)	Hot, windy
81–90	Inclement weather	Precipitation (snow)	Precipitation (normal for season)	Hot, windy
91–99	Storm	Snowstorm	Thunderstorm, snowstorm	Duststorm
100	Powerful storm	Blizzard	Windstorm, blizzard, hurricane, tornado	Downpour

1 Temperate includes forests, hills, marshes, mountains, plains, and warm aquatic environments.

2 Winter is cold, summer is warm, spring and autumn are temperate. Marsh regions are slightly warmer in winter.

Calm: Wind speeds are light (0 to 10 mph).

Cold: Between 0° and 40° Fahrenheit during the day, 10 to 20 degrees colder at night.

Cold Snap: Lowers temperature by –10° F.

Downpour: Treat as rain (see Precipitation, below), but conceals as fog. Can create floods. A downpour lasts for 2d4 hours.

Heat Wave: Raises temperature by +10° F.

Hot: Between 85° and 110° Fahrenheit during the day, 10 to 20 degrees colder at night.

Moderate: Between 40° and 60° Fahrenheit during the day, 10 to 20 degrees colder at night.

Powerful Storm (Windstorm/Blizzard/Hurricane/ Tornado): Wind speeds are over 50 mph (see Table 13–10). In addition, blizzards are accompanied by heavy snow (1d3 feet), and hurricanes are accompanied by downpours. Windstorms last for 1d6 hours. Blizzards last for 1d3 days. Hurricanes can last for up to a week, but their major impact on characters comes in a 24-to-48-hour period when the center of the storm moves through their area. Tornadoes are very short-lived (1d6 × 10 minutes), typically forming as part of a thunderstorm system.

Precipitation: Roll d% to determine whether the precipitation is fog (01–30), rain/snow (31–90), or sleet/hail (91–00). Snow and sleet occur only when the temperature is 30° Fahrenheit or below. Most precipitation lasts for 2d4 hours. By contrast, hail lasts for only 1d20 minutes but usually accompanies 1d4 hours of rain.

Storm (Duststorm/Snowstorm/Thunderstorm): Wind speeds are severe (30 to 50 mph) and visibility is cut by three-quarters. Storms last for 2d4–1 hours. See Storms, below, for more details.

Warm: Between 60° and 85° Fahrenheit during the day, 10 to 20 degrees colder at night.

Windy: Wind speeds are moderate to strong (10 to 30 mph); see Table 13–10.

Fog

Whether in the form of a low-lying cloud or a mist rising from the ground, fog obscures all sight beyond 5 feet, including darkvision. Creatures 5 feet away have concealment (attacks by or against them have a 20% miss chance).