Rain And Snow

Rain reduces visibility ranges by half, resulting in a –4 penalty to Perception checks. It has the same effect on flames and Perception checks as severe wind (see below).

Falling snow has the same effects on visibility and skill checks as rain. Snow-covered squares count as difficult terrain. A day of snowfall leaves 1d6 inches of snow on the ground.

Heavy snow has the same effects as normal snowfall but also restricts visibility as fog does (see Fog on page 399). A day of heavy snow leaves 1d4 feet of snow on the ground. Snow at this depth counts as difficult terrain, and it costs 4 squares of movement to enter a square covered with heavy snow. Heavy snow accompanied by strong or severe winds might result in snowdrifts 1d4×5 feet deep, especially in and around objects big enough to deflect the wind—a reinforced wall or a large force field, for instance. There’s a 10% chance that a heavy snowfall is accompanied by lightning (see Thunderstorm on page 399).

There are other forms of precipitation, such as freezing rain, hail, and sleet. These generally function as rain when falling, but at the GM’s discretion, they may also have effects on movement similar to snow once they accumulate on the ground.