Planning for the weather is an important factor for making your trip to Grevena a success, especially when you're splurging. 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.