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 Cao Bang: The hottest months are usually July and June, with an average temperature of 25°C, while the coldest months are January and December, with an average of 15°C. The rainiest months in Cao Bang are June, August, July and May, with each month seeing an average of 309 mm of rainfall.