The climate is mainly tropical, with variations due to altitude. Kakamega district is mainly hot and wet most of the year, while Bungoma district is colder but just as wet. Busia district is the warmest, while the hilly Vihiga District is the coldest. The entire province experiences very heavy rainfall all year round, with the long rains in the earlier months of the year.
Western Province has diverse physical features, from the hills of northern Bungoma district to the plains bordering Lake Victoria in Busia District. The highest point in Western Province is the peak of Mount Elgon, while the lowest point is the town of Busia on the water at Lake Victoria.