If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in San Antero: The hottest months are usually February and March with an average temp of 82°F, while the coldest months are November and December with an average of 80°F. The rainiest months in San Antero are August, May, July, and June, with each month seeing an average of 11 inches of rainfall.