Rates Of Weathering Because water is an important agent in chemical weathering, the degree of weathering is related to the amount of water existing in the natural environment. The rate that a rock will weather is primarily controlled by the climate. If you have a very wet, moist climate, you have a lot more chemical weathering. The rocks will literally decompose at an accelerated rate. If it's a dry climate, only mechanical weathering will be able to operate, and that's a much more slower process to create soils. In addition to water, temperature is important, because warmer temperatures mean faster chemical reactions. As a result, weathering in the tropics is very rapid. Most deserts are also warm places, but here, the absence of water slows chemical weathering. Eventually most types of minerals chemically weather, or decompose, when they are at or near earth's surface. Source: U.S. Geological Survey