If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Grevena: The hottest months are usually July and August, with an average temperature of 20°C, while the coldest months are January and February, with an average of 3°C. The rainiest months in Grevena are November, January, December and February, with each month seeing an average of 195 mm of rainfall.