There are loads of questions about what's the weather like during each and every month of the year. This website will give you the history of temperatures, wind, rain, sea pressure for every day for the past 11 years - just put in the dates that you want to search ( put in random dates in April as an example).

 http://www.wunderground.com/history/a...

Kenya's climate varies across the country, from the tropical humidity of the coast, the dry heat of the savannah or semi-arid areas and the cool air of the highlands. Temperatures in these areas are fairly constant year round with an average of 27°C (80°F) at the coast, 21°C to 27°C (70°F to 80°F) in the hinterland, while in Nairobi and the highlands over 5,000 ft, the daytime temperatures normally range between 19°C and 24°C (66°F to 75°F). Most parts of the country experience two rainy seasons: the 'long rains' falling over a ten week period between April and June, and the 'short rains' over a five week period between November and December. The rain tends to fall mainly at night and is usually a short and heavy tropical downpour. Rain may occasionally fall outside of the normal rainy seasons. In the highland areas north of Nairobi it may get chilly at night or in the early mornings - especially June, July, August when temperatures are cooler.

Always a difficult one with global  changes etc:

January

February       :Expect little or no rain with the coast experiencing its highest temperatures long hot sunny days

March

April

May

June

July

August               : Expect a short  shower early morning or afternoon but not always! they will dry up in minutes,hot good sunbathing weather!

September       : very similar to August

October

November

December

Expect the wildebeast migration in Kenya around Aug/Sept; you will need to book camps and lodges early around these times as the best ones will have already been booked. Although Tsavo will be fine to book on arrival if you wish, but again some lodges may be full (but not likely).

Here is a website with the latest weather forecast information:

Kenya Meteorological Department