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 temperature of 28°C, while the coldest months are August and July, with an average of 26°C. The rainiest months in Porto-Novo are June, September, October and July, with each month seeing an average of 206 mm of rainfall.