Official Holidays are still in considerable flux. Here is the current list for Saint Petersburg.

1 Jan - New Year's Day
7 Jan - Russian Orthodox Christmas
8 March - International Women's Day
March-May - Russian Orthodox Easter (Paskha)
1 & 2 May - Day of Spring and Labor
9 May - Victory (1945) Day
12 June - Independence Day for Russia
7 & 8 Nov - Day of National Reconciliation and Agreement (former October Revolution day).
12 Dec - Day of Russian Constitution.

TYP Note: If a holiday falls on Thursday, then Friday and Saturday may also be holidays. If a holiday falls on Saturday or Sunday, then Monday will be a holiday.

Other Special Days: There are some other special days in St. Petersburg.
January 18 is the anniversary of Breaking the Blockade of Leningrad in 1943.
January 27 is the anniversary of the complete liberation of Leningrad in 1944.
February 23 is the Day of Fatherland Defenders which is the day of men. Women traditionally give men small gifts on this day. The favor is returned on International Women’s Day which is an official holiday.
May 27 is St. Petersburg Day.
Last Sunday in July is Navy Day, heralded by the appearance of ships in the Neva basin.

Religious Holidays, see CHURCHES, RUSSIAN ORTHODOX

School & University Vacations: Schools start September 1 and finish May 31 with one week vacation in November, two weeks in January at the New Year and one week in March.
Universities usually start the fall semester about September 1 and classes end the 20th of December, followed by examinations in January. Winter break is from the 25th of January to 8th of February. Spring semester starts on the second week of February. Classes finish at the end of May followed by exams until about the 25th of June.

Vacation: Most workers are entitled to 24 days of paid vacation. Many people spend their weekends and vacation in the summer at the dacha. The 1st of May holiday is the traditional day for opening dachas.