If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Ciudad Valles: The hottest months are usually May and June, with an average temperature of 28°C, while the coldest months are January and December, with an average of 20°C. The rainiest months in Ciudad Valles are September, July, June and August, with each month seeing an average of 196 mm of rainfall.