The best time to visit Kenya is during the dry season from June to October when temperatures are comfortable and game concentrations are at their highest. The bush is at its most sparse and waterholes draw wildlife to camera-happy spots.
Kenya’s seasons are predominantly ruled by the ITCZ (Intertropical Convergence Zone), where the northeast and southeast trade winds meet. The resulting effect of this meteorological zone is a pattern of rainy and dry seasons, rather than summer and winter. Traditionally this has brought rains to most of Kenya twice a year the long rains in late March to late May, and shorter rains in October and November.
These two rainy seasons you’ll probably want to avoid for your Kenya safari (unless you can convince your kids that birding is really fun). You’re unlikely to spot a great deal of game because the bush is thick and wildlife is camouflaged and rain isn’t particularly pleasant for you or your surprise bush breakfasts and sundowners.
Having said this, it doesn’t tend to rain all day, and prices along with tourist numbers drop significantly. April and May are the wettest months and not traditionally the best time to take a Kenya safari vacation. On the other hand accommodation rates are at their lowest and the air is incredibly clear which pleases serious photographers. However, be prepared for some tented safari camp enclosures.
The Great Migration moves into the Kenya Mara around July/August usually, staying in Kenya for around 2-3 months until it heads south of the border around October/November. Predicting what is likely to be happening in Kenya on any given month is no exact science, so you do need to be flexible in travel plans and mind and you do need to prep your kids so that sometimes you won’t see a thing on a game drive.
The weather has become increasingly erratic in Africa, having been stable for many generations. Kenya reliably experienced drought every 10 years (late and sporadic rains), and we could predict this and the localized effects this would have. Over the last 40 years, there has been less of a pattern as the frequency of drought years has escalated.