The climate is generally warm and moist. Average temperature during the day is 30°C / 86F. The nights are cool.
Dry season starts in July and ends in February. Rainy season is from March until June, so depending on the season it is advisable to; pack lightweight between 15 to 20 Kilograms, washable clothes plus a sweater for early morning game drives as well as a sun hat, sunglasses and sunscreen. Long sleeves and trousers/pants in light-coloured fabrics to help discourage insect bites.
You can buy clothes in Dar es Salaam and Arusha. Shorts for women are acceptable (but not too short). Women should carry a wrap to cover legs in the villages and towns as revealing clothes can cause offence, especially in Zanzibar and Muslim areas. On the beach and within the confines of the hotels normal swimwear is acceptable (but not nudity).
In colder areas such as Ngorongoro and for climbing Kilimanjaro or Meru, take thermal underclothes in light layers, sweater, rain jacket, good socks and sturdy boots.