Weather is probably a major factor when you plan your trip to Petersburg, 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 12°C, while the coldest months are February and December, with an average of -2°C. The snowiest months in Petersburg are February, January, December and March, with each month seeing an average of 49 cm of snowfall.