If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Arcos: The hottest months are usually August and July with an average temp of 68°F, while the coldest months are February and January with an average of 52°F. The rainiest months in Arcos are October, December, November, and January, with each month seeing an average of 8 inches of rainfall.