If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Cozumel: The hottest months are usually August and July with an average temp of 83°F, while the coldest months are January and February with an average of 77°F. The rainiest months in Cozumel are June, September, October, and August, with each month seeing an average of 8 inches of rainfall.