Planning for the weather is a good way to make your trip to Porto-Novo relaxing and enjoyable, especially when you're splurging. The hottest months are usually January and February with an average temp of 83°F, while the coldest months are August and July with an average of 79°F. The rainiest months in Porto-Novo are June, September, October, and July, with each month seeing an average of 8 inches of rainfall.