Kenya enjoys a tropical climate which varies with topographical regions. There is plenty of sunshine all the year round although rainfall occurs seasonally throughout most of Kenya. The coast, eastern plateaus, and Lake Basin experience two rainy seasons
The long rains occur from April to June and short rains from October to December. The rainfall is sometimes heavy and when it does come it often falls in the afternoons and evenings. The hottest period is from February to March and coldest in July to August.
The climate along the coast is tropical which means rainfall and temperatures are higher throughout the year. Further inside Kenya, the climate is temperate while the northern and northeastern parts of the country experience an arid climate – nearly devoid of rainfall, and temperature swings widely according to the general time of the day/night With the tropical climate of Kenya, summer clothes are worn throughout the year. However, it is usually cool to cold at night and early in the morning.
Tanzania has a pleasant tropical climate but has large regional climatic variations influenced by several factors, including altitude. Temperatures drop by about 6.5°C for every 1000m you climb (or 3.5°F per 1000ft). The hottest and most humid part of the country is on the coast. Other low lying areas, such as the western and southern parks, are also hot but much less humid. The rest of the interior is much milder and cools down significantly at night. Tanzania is too close to the equator to experience a real winter and summer. There is, however, a dry and wet season.
Dry season occur from June to October and there is virtually no rainfall during the whole winter and humidity is very low. When water becomes scarce wildlife will gather around predictable water resources Wet season is from November to May and during most of the wet season, afternoon temperatures are more consistent throughout the country (a bit above or below 30°C/86°F) but will be colder above 1300m/4265ft. Morning temperatures are more moderate, but still cold in most northern parks due to the high altitude. It is advised to pack a windproof jacket and warm sweater for early morning game drives in open vehicles.
Straddling the equator, there is little year round fluctuation in temperature and no real winter or summer. The hottest months are January and February when the average daytime range is 24-33°C (52-91°F) with peaks of up to 40°C/104°F in the far north. The south has two wet seasons: from mid September to November and March to May. The dry season from December to February means only that it rains less and the gorilla parks remain fairly wet during these months. The second dry season- from June and July is considerably drier. Still, with 1000 to 2000 mm of rain every year, it can rain at almost any time. The north, including Murchison Falls and Kidepo Valley, has one continuous wet season from March to November and a more obvious dry season from December to February.
Despite its proximity to the equator, due to the high altitude of most of the country, Rwanda has a temperate climate with temperatures not often above 25 temperature. The long dry season is from June to September and there are two annual rainy seasons, the first from mid-March until the beginning of June and small rains from mid-September to December. The best time for gorilla and monkey tracking is the dry season - if only to spare you getting drenched (you can still see them in the rain, they just get a bit grumpy). The dry season is also good if you want to see game in Akagera National Park because thirst will draw the animals to the watering holes. You will also find at this time the roads are less dangerous and the risk of malaria is lower. The rainy season is the best time to see chimpanzees and is also the time when the place is at its most lush and green.