Here is a rough month by month shape, though wildlife never reads a calendar precisely.

January to March: the herds are generally in the southern Serengeti and Ndutu area, and this is calving season, typically peaking in February, with hundreds of thousands of wildebeest calves born within a short window. Predator action around the calving grounds is exceptional. This is also one of the best times for a Tanzania and Zanzibar combination, since it falls in a drier, warmer stretch on the islands too.

April and May: the long rains fall across much of Tanzania. Some camps close, roads get harder going, but it is also the quietest and cheapest time to visit if you do not mind rain interruptions, and the landscape is at its greenest.

June and July: the herds move north through the central and western Serengeti, often including dramatic Grumeti River crossings around June and July.

August to October: the migration crosses into Kenya’s Mara, so the northern Serengeti still sees good crossing activity at the Mara River on the Tanzanian side, particularly in August, before the herds move fully into Kenya.

November: short rains begin and the herds start moving back south, a genuine shoulder season with fewer crowds and green scenery returning.

December: the herds continue south towards the calving grounds again, closing the annual cycle.

If your main goal is the migration specifically, tell us roughly when you are travelling and we can point you to the part of the Serengeti most likely to have herds present that month, since “the Serengeti” covers a genuinely vast area and being in the right zone matters more than the general season.