Weather is probably a major factor when you plan your trip to Trpanj, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July with an average temp of 75°F, while the coldest months are January and February with an average of 51°F. The rainiest months in Trpanj are November, December, October, and January, with each month seeing an average of 7 inches of rainfall.