Storms

The combined effects of precipitation (or dust) and wind that accompany all storms reduce visibility ranges by three-quarters, imposing a –8 penalty on Perception checks. Storms make ranged weapon attacks impossible, except for those using siege weapons, which have a –4 penalty on attack rolls. They automatically extinguish candles, torches, and similar unprotected flames. They cause protected flames, such as those of lanterns, to dance wildly and have a 50% chance to extinguish these lights. See Table 13–10 for possible consequences to creatures caught outside without shelter during such a storm. Storms are divided into the following three types.

Duststorm (CR 3): These desert storms differ from other storms in that they have no precipitation. Instead, a duststorm blows fine grains of sand that obscure vision, smother unprotected flames, and can even choke protected flames (50% chance). Most duststorms are accompanied by severe winds and leave behind a deposit of 1d6 inches of sand. There is a 10% chance for a greater duststorm to be accompanied by windstorm-magnitude winds (see Table 13–10). These greater duststorms deal 1d3 points of nonlethal damage each round to anyone caught out in the open without shelter and also pose a choking hazard (see Drowning, except that a character with a scarf or similar protection across her mouth and nose does not begin to choke until after a number of rounds equal to 10 + her Constitution score). Greater duststorms leave 2d3–1 feet of fine sand in their wake.

Snowstorm: In addition to the wind and precipitation common to other storms, snowstorms leave 1d6 inches of snow on the ground afterward.

Thunderstorm: In addition to wind and precipitation (usually rain, but sometimes also hail), thunderstorms are accompanied by lightning that can pose a hazard to characters without proper shelter (especially those in metal armor). As a rule of thumb, assume one bolt per minute for a 1-hour period at the center of the storm. Each bolt causes between 4d8 and 10d8 points of electricity damage. One in 10 thunderstorms is accompanied by a tornado.

Powerful Storms: Very high winds and torrential precipitation reduce visibility to zero, making Perception checks and all ranged weapon attacks impossible. Unprotected flames are automatically extinguished, and protected flames have a 75% chance of being doused. Creatures caught in the area must make a Fortitude save or face the effects based on the size of the creature (see Table 13–10). Powerful storms are divided into the following four types.

Windstorm: While accompanied by little or no precipitation, windstorms can cause considerable damage simply through the force of their winds.

Blizzard: The combination of high winds, heavy snow (typically 1d3 feet), and bitter cold make blizzards deadly for all who are unprepared for them.

Table 13–10: Wind Effects

Wind Force	Wind Speed	Ranged Attacks Normal/Siege Weapons¹	Checked Size²	Blown Away Size³	Fly Penalty
Light	0–10 mph	—/—	—	—	—
Moderate	11–20 mph	—/—	—	—	—
Strong	21–30 mph	–2/—	Tiny	—	–2
Severe	31–50 mph	–4/—	Small	Tiny	–4
Windstorm	51–74 mph	Impossible/–4	Medium	Small	–8
Hurricane	75–174 mph	Impossible/–8	Large	Medium	–12
Tornado	175–300 mph	Impossible/impossible	Huge	Large	–16
1		The siege weapon category includes ballista and catapult attacks as well as boulders tossed by giants.
2		Checked Size: Creatures of this size or smaller are unable to move forward against the force of the wind unless they succeed on a DC
		10 Strength check (if on the ground) or a DC 20 Fly skill check if airborne.
3		Blown Away Size: Creatures on the ground are knocked prone and rolled 1d4 × 10 feet, taking 1d4 points of nonlethal damage per

10 feet, unless they make a DC 15 Strength check. Flying creatures are blown back 2d6 × 10 feet and take 2d6 points of nonlethal damage due to battering and buffeting, unless they succeed on a DC 25 Fly skill check.

Hurricane: In addition to very high winds and heavy rain, hurricanes are accompanied by floods. Most adventuring activity is impossible under such conditions.

Tornado: In addition to incredibly high winds, tornadoes can severely injure and kill those that get pulled into their funnels.