If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Longmen County: The hottest months are usually August and July with an average temp of 82°F, while the coldest months are January and December with an average of 61°F. The rainiest months in Longmen County are June, May, August, and July, with each month seeing an average of 14 inches of rainfall.