Two dry seasons, two wet seasons
Most of East Africa runs on the same broad rhythm: a long dry season from June to September or October, a short dry spell from December to February, and two rainy interludes in between — the “long rains” from March to May and the “short rains” in November. Altitude and location shift this by a few weeks in either direction, and Ethiopia, further north and higher up, runs on a different clock again.
January – February
Short dry season across Kenya and Tanzania. This is calving season on the southern Serengeti plains around Ndutu, where several hundred thousand wildebeest calves are born within a few weeks, drawing predators in close. Also a strong window for gorilla trekking in Uganda and Rwanda, with clear trails and good visibility.
March – May
The long rains. Roads soften, some camps close, and gorilla permits in Bwindi are sometimes discounted for this quieter period. Not a write-off — the forest is at its most vivid, and birding is excellent — but game drives get muddier and the migration herds are on the move north through the central Serengeti.
June – July
The long dry season begins. Grass shortens, water concentrates wildlife around rivers and waterholes, and visibility opens up across the savannah parks. The migration reaches the western corridor of the Serengeti and the Grumeti River crossings become possible, though never guaranteed on any given day.
August – September
Peak dry season and peak demand. This is when the migration is most likely to be crossing the Mara River between the northern Serengeti and the Maasai Mara, when Bwindi’s trails are firmest, and when Kilimanjaro sees its highest summit-attempt volumes. Book six months or more ahead for gorilla permits and Mara conservancy accommodation.
October – November
The short rains arrive, usually as brief afternoon downpours rather than all-day rain. The migration herds start drifting back south. Zanzibar gets its own short rainy spell too, though beach days are still common between showers. A genuinely good value window — fewer vehicles, still-decent conditions.
December
The short dry season returns, holidays push prices up sharply in the last two weeks, and the migration herds are settling back into the southern Serengeti ahead of calving. Zanzibar’s dry, hot season runs roughly December through February and is the busiest beach period.
Where the seasons matter less
Gorilla and chimp trekking happen year-round because primates do not migrate on a seasonal cycle — the family you trek to is roughly where it was the week before, rain or shine. The dry months just mean firmer, less slippery trails, not a better chance of a sighting. Birding is similarly good most of the year, and actually improves from November to April when Palearctic migrants join the resident species.
The mistake worth avoiding
Booking a Serengeti trip in July specifically to see “the crossing” is the single most common planning error. The Mara River crossings cluster in August and September most years, but herds have crossed in July and stayed put until October in others. Rainfall drives the migration, not the calendar, and rainfall does not read tour brochures.
Zanzibar and the coast run their own calendar
The Indian Ocean coast follows a simpler pattern than the mainland’s rift-valley weather. December to February is hot and largely dry, the busiest and most expensive beach period. June to October is drier again and slightly cooler, popular with travellers pairing a mainland safari with a few coastal nights afterwards. The long rains from March to May bring the heaviest showers, often as short, heavy bursts rather than washed-out days, and this is when beach resort rates drop furthest.
Ethiopia, on a different clock
Ethiopia’s highlands sit at a different altitude and latitude to the rest of this list, and its dry season runs October to May with the wettest months in June, July and August — more or less the reverse of the Serengeti’s peak season. A trip combining an East Africa safari with Ethiopia’s historic route needs its own separate weather check, not an assumption that the same months apply.
Booking against the calendar
Gorilla permits and Mara conservancy accommodation for the August-September peak routinely sell out six months or more ahead. The shoulder months either side — June, early July, late September, October — offer nearly identical conditions with more availability and, often, lower rates. If your dates are flexible by even two or three weeks, that flexibility is worth more than almost any other planning decision you will make.
