It might get quite windy too. At any rate, weather forecasts on TV and radio always get the highest ratings. St. Petersburg's climate is mild compared to that of the more inland areas of Russia. The city is on the Baltic Sea, which makes winters relatively mild, but summers are not particularly hot either. It is humid all year round.
Winters are long as in most areas of Russia.
The average winter temperature is -6.9 C o . The Neva River freezes between November 25 and December 5 and the ice is gone only by mid-April. Springs can be quite long. From early April temperatures are above freezing and by April 15 all the snow normally melts. One should be prepared for some chilly rainy days, but it can get rather warm mid-May onwards.