More travellers ask us "when should I come for the migration?" than any other question — and almost all of them picture the same thing: a wall of wildebeest plunging into a crocodile-filled river. That moment is real. But it is one chapter of a story that runs all year, in a great clockwise loop between Tanzania and Kenya. Get the timing right and you don't just see the migration — you see the part of it you actually came for.
The Great Migration isn't an event with a start date. It's roughly 1.5 million wildebeest, plus several hundred thousand zebra and gazelle, following the rains and fresh grass in a continuous circuit through the Serengeti-Mara ecosystem. The animals don't read calendars, so treat every month below as a strong probability, not a guarantee — and build a couple of flexible days into any trip timed around it.
December to March — Calving season in the southern Serengeti
The herds gather on the short-grass plains around Ndutu and the southern Serengeti. In a roughly three-week window centred on late January and February, around 8,000 calves are born every day. It is the most underrated time to come: enormous concentrations of animals, newborns finding their legs, and the highest predator action of the year as lions, cheetah and hyena work the edges of the herds. If raw drama is what you're after and you don't mind it being in Tanzania rather than Kenya, this is it.
April and May — The long rains and the move north
The green season. The herds begin drifting north-west through the central Serengeti. Afternoon showers keep the landscape luminous and the crowds thin, and lodge rates drop noticeably. You'll trade some predictability for lower prices and softer light — a fair deal for photographers and anyone travelling on a budget who still wants big game.
The one-line version
River crossings into Kenya's Maasai Mara peak July to October. Calving in the southern Serengeti peaks late January to February. Everything else is the herd travelling between the two.
June — The rut, and the build toward the Grumeti
As the plains dry, columns of wildebeest mass in the western and northern Serengeti. June brings the rut — males sparring, the air full of that famous grunting — and the first tense crossings of the Grumeti River. It's a quieter, atmospheric month before the high-season rush.
July to October — River crossings in the Maasai Mara
This is the postcard. The herds reach the Mara River on the Kenya–Tanzania border and must cross, again and again, where Nile crocodiles wait. Crossings are unpredictable and unscripted — a herd can build on the bank for an hour and then turn back — so you give it time and let your guide read the signs. The reward is the single most electric thing in African wildlife.
It is also peak season: book camps in the Mara and the northern Serengeti six to twelve months ahead, and expect company at the best crossing points. Staying in a private conservancy bordering the Mara reserve buys you quieter game drives and off-road access while keeping the river within reach.
"People come for the crossing and leave talking about the silence beforehand — a thousand animals on the bank, completely still, deciding."
November — The short rains and the turn south
The short rains green the plains again and the herds begin flowing back down into Tanzania. A lovely shoulder month: fewer vehicles, fresh landscapes, and good value before the December calving cycle begins anew.
So when should you go?
If your heart is set on a river crossing, aim for late July through September and base yourself in the Maasai Mara or a bordering conservancy. If you want maximum wildlife density and predator action with fewer crowds, come for February calving in the southern Serengeti. And if you want the best light and the best price, the April–May and November green seasons are quietly brilliant.
Whichever window you choose, the trick is the same: stay close to where the herds will be, give the wildlife time, and travel with a guide who knows the ecosystem rather than a fixed itinerary. That's the part we handle.
