If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Trincomalee: The hottest months are usually April and May with an average temp of 81°F, while the coldest months are January and February with an average of 76°F. The rainiest months in Trincomalee are November, December, October, and January, with each month seeing an average of 10 inches of rainfall.