Located close to the equator, temperatures in Rwanda remain fairly constant throughout the year. The temperature is largely controlled by elevation and all of Rwanda is at elevation, the lowest point in the country is over 3000 feet. Gorilla trekking areas range from 7500 - 9500 feet.
Temperatures in Kigali hover around 70 degrees year round, with variations usually no more than 10 degrees above or below that number. Volcanoes National Park can be 10 degrees or more cooler, so plan to bring layers for gorilla trekking. There are two rainy seasons in the year, one from April to May and the other in November. In the high altitude rain forests it can rain at any time of the year, and it does. The two dry seasons are from December to March and from June to October