If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Sai Kung: The hottest months are usually August and July with an average temp of 84°F, while the coldest months are January and December with an average of 65°F. The rainiest months in Sai Kung are August, June, July, and May, with each month seeing an average of 13 inches of rainfall.