Planning for the weather is a good way to make your trip to Harbour Grace relaxing and enjoyable, especially when you're splurging. The hottest months are usually August and July with an average temp of 56°F, while the coldest months are February and January with an average of 30°F. The snowiest months in Harbour Grace are March, February, January, and December, with each month seeing an average of 30 inches of snowfall.