The climate is diverse as a result of the proximity of the ocean and inland lakes, the wide altitudinal range, and latitude, which govern temperature. It is characterized by two main rain seasons: the long rains (Masika) and the short rains (Vuli), which are associated with the southward and northward movements of the Inter-Tropical Convergence Zone (ITCZ).

The long rains begin in mid-March and end in May, while the short rains begin in mid-October and end in early December. The northern part of the country, including areas around the Lake Victoria Basin, the North-Eastern Highlands, and the Northern Coast, experiences a bimodal rainfall regime. Central, South, and Western areas have a prolonged unimodal rainfall regime starting from November to the end of April.

In general, annual rainfall varies from 550 mm in the central part of the country up to 3690 mm in some parts of the south-western highlands. Most of the country receives less than 1,000mm, except the highlands and parts of the extreme south and west, where 1,400 to 2,000mm can be expected. The average annual rainfall in the central regions is around 600mm.

Temperature varies according to geographical location, relief, and altitude. Along the coast and in the off-shore islands, the average temperature ranges between 27°C and 29°C, while in the central, northern, and western parts, temperatures range between 20°C and 30°C. Temperatures are higher between the months of December and March and coolest between June and July. In the Southern highlands and mountainous areas of the north and northeast, temperatures occasionally drop below 15°C at night, and in the cold months of June and July, sub-zero temperatures can also be experienced.