Planning for the weather is a good way to make your trip to Giresun relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 69°F, while the coldest months are January and February with an average of 45°F. The rainiest months in Giresun are October, June, May, and September, with each month seeing an average of 8 inches of rainfall.