If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Chertsey: The hottest months are usually July and August with an average temp of 62°F, while the coldest months are January and February with an average of 18°F. The snowiest months in Chertsey are January, February, December, and March, with each month seeing an average of 24 inches of snowfall.