Planning for the weather is a good way to make your trip to Cozumel relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July, with an average temperature of 28°C, while the coldest months are January and February, with an average of 25°C. The rainiest months in Cozumel are June, September, October and August, with each month seeing an average of 213 mm of rainfall.