It's been two years since I went on this trip and every time I see someone posting a reply I'm rejoicing. Thanks again for your numerous replies and kind comments (although I'm a rare poster
About the time to visit... Between June and August you have to be really unlucky to see snow.
I am in Murmansk as I'm writing this and my friends here told me that the last summer was pretty bad; even in July the temperatures only rarely rose above 10°C. On the other hand, this summer the north has been hit by a heat wave and since I'm here, it has never been colder than 20°C.
So while the general advice would be that July usually is your best bet, there's no guarantee at all.
Another factor for some is the polar day, when the sun never sinks below the horizon. In Murmansk, it's from 18 May to 24 June. I arrived later and, frankly, it's not really a difference, since the sun sinks behind mountains anyway and it's still bright now at midnight. But of course, by the end of August, it will get dark and cold again by night.
Regarding the mosquitoes, don't think about bringing stuff from your home. The karelian mosquitoes just laughed at my spray from Switzerland, I just rubbed myself in what they thought to be spices. Buy the real stuff in a Russian shop, like рефтамид (Reftamid). It's the military formula and is available in chocolate taste (
), but it works incredibly good. Also spray your clothes and socks, because otherwise they bite through it!
In comparison to two years ago, the main road M18 between Piter and Murmansk is getting better and better. There are still a few dozen kilometres of bumpy roads and road works where it's only gravel, but pretty much every bike can handle it. So enjoy your trip to the north! :-)