Tanzania's Weather is cool in certain areas, specifically in the highlands and mountainous spots like Mount Kilimanjaro. The temperatures at better elevations is often rather chilly, Primarily during the night time, and should even drop below freezing. Humidity: There is some humidity during January, notably in coastal areas like Zanzibar, https://www.zepisaafricansafaris.com/tanzania-in-january-weather-for-safari/