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Migration · 7 min read

The Grumeti River migration: June in the Western Corridor

June in the Western Corridor, with a fraction of the vehicles.

Active Kili Top · Arusha · Updated 3 October 2026
Two wildebeest facing the camera with the herd behind them on dry grass
Wildebeest on the move in the dry season.

The Grumeti River migration is the stage most itineraries skip. Between the calving in the south and the famous crossings in the north, the herds spend a few weeks in the Serengeti’s Western Corridor, a long arm of the park that reaches towards Lake Victoria. The Grumeti runs down the middle of it, and around June it is the first river the wildebeest have to deal with.

It is a quieter event than the Mara in every sense: fewer animals in the water at once, fewer camps, fewer vehicles, and less certainty. This article explains where the corridor is, when the herds pass through, what a Grumeti crossing looks like, and when the west is and is not worth the detour. For the whole year in one table, see our wildebeest migration calendar.

The short answer

The migration usually reaches the Grumeti River, in the Serengeti’s Western Corridor, in late May and June, on its way north. The river is a chain of pools and channels with large crocodiles, so crossings are smaller and less certain than on the Mara River, but far fewer vehicles are there to watch them.

At a glance: the Grumeti River migration and the Mara compared

Timing moves with the rains. In some years most of the herds bypass the west or pass through quickly.
Grumeti RiverMara River
Usual monthsLate May to early JulyJuly to October
Part of the SerengetiWestern CorridorThe far north, around Kogatende
The riverPools and channels; often not flowingA wide river that flows all year
CrossingsSmall, scattered, easy to missLarge, repeated, in both directions
VehiclesFewMany in August
How long the herds stayDays to a few weeksAbout three months, back and forth
Next: The Western Corridor ↓Contents ↑

Where the Grumeti River and the Western Corridor are

Look at a map of the Serengeti and you will see a finger of park pointing west from the centre towards Lake Victoria. That is the Western Corridor. It ends at Ndabaka gate, close to the lake shore and about two and a half hours by road from Mwanza. From Seronera, in the middle of the park, it is a drive of roughly three hours on park tracks to the Kirawira area.

The Grumeti River flows west along the corridor to the lake. It is lined with a band of tall riverine forest, which is unusual in a park known for open grass, and black-and-white colobus monkeys live in the canopy. Either side of the river are open plains, low hills and patches of woodland, with resident game all year.

North of the corridor, outside the national park, lie the Grumeti and Ikorongo game reserves, which are run as a private concession with their own lodges and rules. People often mix the two up. When we write about the Western Corridor here we mean the part inside the national park, which any visitor with a park permit can drive.

Next: The months ↓Contents ↑

When the migration reaches the Grumeti River: May to July

The herds leave the southern plains as the long rains end, pass through the central Serengeti in April and May, and turn north-west. The front of the migration usually reaches the Western Corridor in late May, and June is the month most associated with it. By early July the bulk has normally moved on, north through the Grumeti reserves and the Ikoma area towards the Mara River.

This is the loosest part of the calendar. The wildebeest are travelling, not settled, and they move in long columns that can be many kilometres from end to end. Some years they linger in the west for weeks. In others they hurry through, or a large part of the migration takes a more easterly line and misses the corridor. Unseasonal rain in the south can hold them back altogether, as it did in 2014.

June is also when the rut is at its height. The park authority says about 300,000 cows conceive in less than a month, and the bulls spend it marking out small temporary territories, chasing rivals and grunting day and night. It is noisy and restless, and it gives the herds in the west a different character from the quiet grazing herds of the calving season in Ndutu.

Next: The crossings ↓Contents ↑

Grumeti River crossings: smaller than the Mara, and why

Do not expect the Mara. By June the Grumeti has usually stopped flowing along much of its length and become a chain of pools and channels. A herd can often walk across a dry stretch or around a pool, and many do. Where the water is deep enough to matter, groups come down to drink and to cross in dozens or hundreds at a time, not in thousands.

What the Grumeti has is crocodiles. The pools hold large Nile crocodiles all year, and the arrival of the herds is their main feeding season. A good deal of what you see at the river is this: wildebeest edging down to drink, backing off, coming down again, and now and then a sudden strike. It is tense, close and slow, and most of it happens at a handful of pools your guide will know.

The honest summary is that a Grumeti crossing is a smaller event that is easier to miss. If the picture in your mind is a high bank and a river full of animals, that is the Mara, between July and October, and we explain it in why a river crossing cannot be booked. Go west in June for herds on the move, the rut and the river, in that order.

Next: Why it is quieter ↓Contents ↑

Why the Western Corridor is quieter than the Mara River

The card for this article says a fraction of the vehicles, and that is fair. Three things account for it. The first is timing: June falls just before the main holiday season, while the Mara crossings coincide with July and August, the busiest months of the year in Tanzania. The second is the short and uncertain window, which makes it hard for anyone to sell.

The third is distance. Most Serengeti safaris from Arusha enter by Naabi Hill in the south-east, spend their nights around Seronera and leave the same way. The Western Corridor is several hours further on, in the wrong direction for the road home, and it has far fewer camps than the centre or the north. Fewer beds means fewer vehicles at any sighting, whatever the herds are doing.

Quiet has a cost. With fewer vehicles there are fewer eyes looking for the herds, and a guide relies more on his own reading of the ground. Parts of the corridor have tsetse flies, which bite; neutral colours and long sleeves help. And if the migration has already passed, you are a long drive from where it has gone. That is the risk you accept for having the place largely to yourself.

Next: Planning June ↓Contents ↑

How to plan a Western Corridor safari in June

We do not publish a fixed plan based in the Western Corridor, because the window is too short and too variable to print dates against. We build it to order. The usual shape is two or three nights in the west in June added to nights in the central Serengeti, so that you have the resident lion and leopard around Seronera whatever the herds have done. Start from the trip planning page and tell us your dates.

A day trip from Seronera means about six hours of driving for a few hours at the river, so sleep in the west if you go. There is an airstrip at Grumeti served by scheduled light aircraft, so you can fly in from Arusha and drive back through the centre, or the reverse. Our Serengeti Fly-in plan shows how the flying works, and private flying covers the charter option.

Be ready to change the plan. If the herds are early and have gone north by your dates, it makes more sense to move your nights than to sit by an empty river. If they are late, the central Serengeti may have them instead. June is a good month across the north in any case: dry, cool and not yet crowded. The plans that suit the Serengeti in June are listed on the safari plans page.

Next: Questions ↓Contents ↑

Questions people ask

Usually from late May to early July, with June the most likely month. The timing follows the end of the long rains and moves from year to year. In some years the herds stay for weeks, and in others they pass through the Western Corridor in a few days.

No, and it is better to know that beforehand. The Grumeti is usually a chain of pools by June, so crossings are small and scattered. The Mara is a wide, flowing river with repeated mass crossings. The Grumeti’s advantages are large crocodiles at close range and very few vehicles.

It is the arm of the national park that runs west from the central Serengeti towards Lake Victoria, following the Grumeti River. Ndabaka gate is at its western end, about two and a half hours by road from Mwanza. Kirawira is roughly three hours’ drive from Seronera.

In most years the main herds are in the Western Corridor and the western side of the central Serengeti in June, heading north. The front may already be approaching the northern Serengeti by the end of the month. Ask your operator where the herds are a week or two before you travel.

No. The Western Corridor is part of the Serengeti National Park and is open to any visitor with a park permit. The Grumeti and Ikorongo game reserves lie to its north, outside the park, and are run as a private concession with their own lodges.

Yes. Large Nile crocodiles live in the river’s permanent pools all year, and they feed heavily when the wildebeest arrive to drink and cross. Watching them is one of the main reasons to visit the river in June. Hippos share the deeper pools.

Yes. June is the start of the dry season: the weather is cool and clear, the grass is drying, and the busiest weeks have not yet begun. The migration is on the move through the west, so plan nights in two areas.

Last updated 3 October 2026

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