If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Nanjing: The hottest months are usually July and August with an average temp of 79°F, while the coldest months are January and December with an average of 44°F. The rainiest months in Nanjing are July, June, August, and May, with each month seeing an average of 9 inches of rainfall.