Taking the local weather in Saint-Gratien into account can help you maximise your time at the pool during your trip. The hottest months are usually August and July, with an average temperature of 19°C, while the coldest months are January and February, with an average of 6°C. The snowiest months in Saint-Gratien are February, March, January and April, with each month seeing an average of 14 cm of snowfall.