WEATHER CONTROL
The weather sections within each biome are restrictions to the "global" weather condition running across the entire world. For example, if the global weather says the precipitation of the world is 20 and your biome does not have any restrictions that allow below 50 for precipitation, then your biome will have the lowest possible precipitation allowed within its restrictions defined in this file.
Temperature is different. It is the base temperature of the biome to subtract from the global temperature. The final temperature is effected by rain, wind, clouds, and angle of the sun (each of these will only subtract from the temperature).