Inland regions have a temperate, tropical climate, whilst the coast is very humid and can, sometimes, get too hot. The best time to visit Tanzania is during the dry season, which runs from May to October. Avoid the rainy season between March and the beginning of May. Another option is to go during a short rainy season that lasts from November to mid-December. There are fewer tourists and the country is in bloom. All of this depend on what you plan to do when there. The dry season is ideal for safaris in most of the parks, but to see the wildebeest and zebra migration (as well as the predators at large), opt for the rainy season. If you dislike the heat, avoid January and February, the hottest months of the year.