Being situated virtually on the equator, Rwanda enjoys a pleasant climate all year round and can be enjoyably visited in any month of the year. It can be humid and is seldom blistering hot, rather day time temperatures are pleasantly warm, while nights are balmy or cool, especially at the higher altitudes in the west.
Its equatorial position means that Rwanda experiences two rainy seasons a year: the long rainy season lasts from mid-February to early-June, while there is a second shorter rainy season between mid-September and mid-December.
In places like Nyungwe and the Volcanoes National Park which are located at high altitudes and are rain forest environments, you stand the chance of getting wet at any time of the year and it is important that you are prepared and take good rain gear. Tracking gorillas and chimpanzees during the long dry season (June to September) is most popular since the going underfoot is drier and you slip and slide less. December to mid-February is also a popular time to visit for this reason.
Nonetheless there are advantages to visiting outside of the dry season that extend beyond lower tourist numbers. During the rains the country is strikingly beautiful and the fruiting of certain trees during this time can make viewing of primates like chimpanzees even better.