Southern Tanzania June through October. Western Tanzania May through October. Best time to Climb Mount Meru or Mount Kilimanjaro. It can be climbed at any time during the year. However, April, May and November is the rainy season.
Neutral colours are most practical and recommended since the game parks can be dry and dusty.
Plan to dress for outdoor comfort. You will not need dressy or formal clothing of any sort. Do not over pack. Inexpensive laundry service is available at most lodges and hotels in Tanzania. Think in terms of layers, as temperatures are cooler in the early mornings and evenings but warm up during the day.