Overall, Addis Ababa maintains pleasant daytime temperatures year-round, which can range anywhere from 65 to 85 degrees. Temperatures drop at night, sometimes to almost freezing. During the Big Rains especially in July and August the almost constant cloud cover lowers temperatures somewhat.

More specifically, the best time to go may be between early October and March, when the days are typically warm, cloudless, and dry. The April to May period is less predictable - the Little Rains come and can last from 5 days to 6 weeks BUT the rain is showers which can be heavy but are short and will not spoil a holiday at that period.  May is the most humid month in Addis.   Rain is more likely from June through September, when rivers often flood and fog may obscure the views. If you have a choice it is probably best to avoid the Big Rains - especially July August which on average in Addis have 9 and 11 inches of rain respectively!!.