“You can plan a Tanzania safari at any time of year, but the optimal time depends on your interests.” If watching the wildebeest migration is the major reason for your trip, make sure you plan ahead. The greatest time to watch the Serengeti migration is from June to September, but you’ll have to stay in different regions of the park at different periods of the migration, and this isn’t fully predictable because it all depends on the rain.
If you want to avoid the crowds, stay in the Serengeti away from the wildebeest migration. March and April are the wettest months, and any safari during these months may be jeopardized.