Planning for the weather is a good way to make your trip to Cayenne relaxing and enjoyable, especially when you're splurging. The hottest months are usually September and October, with an average temperature of 27°C, while the coldest months are July and January, with an average of 26°C. The rainiest months in Cayenne are May, June, April and December, with each month seeing an average of 432 mm of rainfall.