If you're looking forward to lots of outings with your partner, check out these details about year-round temperatures in Monserrate: The hottest months are usually August and July with an average temp of 67°F, while the coldest months are January and February with an average of 52°F. The rainiest months in Monserrate are October, December, November, and January, with each month seeing an average of 9 inches of rainfall.