Taking into account the local weather in Coquitlam is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually August and July with an average temp of 61°F, while the coldest months are December and February with an average of 37°F. The rainiest months in Coquitlam are November, January, December, and October, with each month seeing an average of 12 inches of rainfall.