If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Cao Bang: The hottest months are usually July and June with an average temp of 78°F, while the coldest months are January and December with an average of 59°F. The rainiest months in Cao Bang are June, August, July, and May, with each month seeing an average of 12 inches of rainfall.