I am on the same cruise travelling with my wife and two sons (10 and 19 years old). This is my second cruise and my first time visiting the Baltic countries. I am expecting temperatures on the region of the 70's. Showers are forecasted for next week. Let's hope that the weather will improve.
Acordind to http://www.cityvision2000.com/city/weather.htm
summers vary from year to year, but generally temperatures are somewhere near +20-25 C. You ought to have some clear days to enjoy the White Nights. Hot sunny days are not rare, but you never know when it is going to rain. July is the hottest month of the year. It usually starts getting a bit cooler in mid-August. The highest temperature ever recorded in the city was +33.6 C.
I am planning to take one excursion including the Hermitage museum one day and another including the Catherine Palace. Also considering stopping to take pictures of the Churches, the Aurora, canals, Peter the great cabin, shopping and if possible visiting the metro. One possibilty is to book a Van and if we could share the Van, it would be great.
Please let me know your comments and suggestions for places to visit to my firstname.lastname@example.org