Geographical particularities
In the southern part of the country, the climate is sub-equatorial (Guinean) and characterized by high humidity. It's not unusual for humidity levels to reach... 94%! From Cotonou to Savé, there can be up to 1,400 mm of rainfall a year. And, in general, average temperatures don't fall below 25°C. On the other hand, as you head northwards, the climate becomes subtropical (or Sudanian), in other words a little warmer and less rainy. Annual rainfall is generally no more than 1,000 mm in the north-west and 850 mm in the north-east. The Atacora mountain range has a special tropical climate, with cooler temperatures and higher rainfall. So don't hesitate to pack a little wool for the evenings if you're planning to spend some time in this region. The average ocean temperature varies between 26°C (August) and 29°C (April and May), but swimming is dangerous whatever the season.
Distinct seasons in the South
These differences in climate between north and south are also reflected in the seasons. The year in the south of the country is punctuated by four seasons.
November to mid-April is the hottest season, a dry season with temperatures ranging from 24 to 30°C, and obviously the season favored by travelers. Between mid-April and mid-July, the country experiences a rainy season, with particularly heavy rainfall in June. Then, good news for summer holidaymakers, the dry season returns from mid-July to mid-September. Finally, from mid-September to November, the south of the country experiences a short rainy season, with temperatures ranging from 24 to 29°C and showers.
A long dry season in the North
Unlike the south, northern Benin has only one rainy season. This is followed by a long dry season in two stages. From mid-October to early March, the region experiences a dry season, but one that is relatively cool, with temperatures varying between 15 and 35°C. This is the period when the harmattan blows, a dry, cold, dust-laden wind from the northeast, which lays an ochre-orange veil over the sun and can sometimes be a little annoying (especially around January).
Then, from early March to mid-May, it's time for the hot, dry season, with temperatures ranging from 21 to 40°C. This is the most pleasant period in the north. Finally, from mid-May to mid-October, the rainy season sets in, with many showers, especially in August. Temperatures range from 22 to 34°C.
