Weather is probably a major factor when you plan your trip to St. Stephen, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and August, with an average temperature of 17°C, while the coldest months are January and February, with an average of -4°C. The snowiest months in St. Stephen are January, February, December and March, with each month seeing an average of 39 cm of snowfall.