Generally, the best time to visit Ethiopia is between October to March when there are pleasant temperatures, blue skies and low rainfall in most parts of the country. The best time to visit Erta Ale, Dallol and the Danakil Depression is between October to February when its soaring temperatures are most tolerable.
Likewise, the best time to visit Simien Mountains National Park is October to March when skies are clear and the sun is strong. A short rainy season occurs February to March when there is likely to be a short period of rain every day. Note that it gets very cold during the night; the Simiens have been described as “summer every day, winter every night”. As such, pack plenty of layers!