Weather

I doubt this is at all realistic, and it's probably too fiddly for most people, but here's a draft of a general weather chart that I'm considering using for this region.

Table: Random Weather
d20	Weather	Wind Table	Temp Table	Precip Table	Temperate Climate
1-13	Normal weather	1d10	1d10	1d6-1	Normal for season
14-15	Abnormal weather	2d6	2d6	2d4	Heat wave (01-50) or cold snap (51-100) 1d8+12 on Temperature Table
16-17	Inclement weather	3d4	3d4	1d4+6	Precipitation (normal for season)
18-19	Storm	1d10+6	1d10+6	1d6+6	Thunderstorm, snowstorm
20*	Powerful storm	1d10+10	1d10+10	1d4+8	Windstorm, blizzard, hurricane, tornado
* Roll d20 again – if abnormal weather is indicated (14-19), the storm is a powerful storm as listed below, if a second 20 is rolled, the storm is a “storm of the century” table listed below.

Wind Table		Temperature Table***		Precipitation Table
1	No Wind 0 mph	1	10 degree change	0	Very dry, cloudless
2-3	Light Wind 0-10 mph	2-3	5 degree change	1	Dry, clouds
4-7	Moderate Wind 11-20 mph	4-7	No change	2-3	Dry, very cloudy
8-10	Variable Winds**	8-9	5 degree change	4-5	Partly cloudy, brief drizzle
11-12	High Winds 20-50 mph	10	10 degree change	6	Rain, 2d4 hours, overcast
13-14	Severe Wind 50-70 mph	11-12	15 degree change	7	Heavy Rain, 3d4 hours
15-16	Dangerous Wind 70-90 mph	13-15	20 degree change	8	Soaking Rain, 2d6 hours, overcast
17	Deadly Wind 90-120 mph	16-17	25 degree change	9	Hard Rain, 3d8 hours, thick cloud cover
18	Hurricane Winds 120-150 mph	18	30 degree change	10	Hard Rain, 2d12 hours including 1 hour of hail, sun-blocking clouds
19	Tornado Winds 150-200 mph	19	40 degree change	11	Hard Rain, 6d4 hours, flooding, sun-blocking clouds
20	Unnatural Winds 200+ mph	20	50 degree change	12	Hard rain, 24 hours, flooding, extreme lightning, sun-blocking clouds
** Variable Winds: Winds blowing from 10-40 (1d4x10) mph with gusts 50-90 mph (1d4+4x10). Check for gusts any time something is attempted that might be adversely affected by winds *** Temperature changes are based on the previous day’s temperatures. Unless otherwise directed, a 50% chance of raising and 50% chance of lowering temperatures.

Storm of the Century
1d8	Temperate Climate
1	Hurricane/Tornado cluster (2d4 tornadoes touch down)3d6+12 inches of rain over 24 hour period, massive flooding
2-4	1d8+4 inches of rain falls for 1d12+12 hours, flooding, cluster lightning
5-7	Hail the size of grapefruits falls for 10d6 minutes (each does 1d6 damage), +1d4+8 inches of rain over 12 hour period, flooding
8	Golf ball sized hail for 10d4 minutes (1 point of damage each), +12d6 inches of rain over 20 hour period, cluster lightning