Weather is probably a major factor when you plan your trip to Lethbridge, 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 February and December, with an average of -4°C. The snowiest months in Lethbridge are February, March, October and April, with each month seeing an average of 14 cm of snowfall.