Hiya dont know but i dont think you will be going as its past june 20/06/08 i think you maybe mean 09 sorry if i sound rude.
It was flippin freezing when I was there in June this year. It was flippin freezing when my work chum went there in August. It was baking hot when another friend did it in July. In short you cannot tell. Take layers and a light rain jacket.
With St Petersburg as far north as the Shetlands we thought it might be a cold trip, but it was t-shirt weather the whole time. As 'Aldrich' says, you just can't tell... (But if you really went in June 08 you already know ;-)).