Kenya and Tanzania are great year round destinations. The main tourist season is in January and February, since the hot, dry weather at this time of year is generally considered to be the most pleasant. It’s also when bird life flocks to the Rift Valley lakes in the greatest numbers. June to September could be called the ‘shoulder season’ as the weather is still dry. The rains hit from March to May (and to a lesser extent from October to December). During these months things are much quieter – places tend to have rooms available and prices may decrease. The rains generally don’t affect travelers’ ability to get around.
Masai Mara Safaris July/August and December are the busiest times in Kenya and Tanzania when parks and lodges get a bit crowded and reservations often must be made at least 6 to 8 months in advance. Travel during rest of the year primarily depends on the weather.