[Halon]

I would think if snow is stopping air from traveling through the radiator, that might be a bad thing.

Also, any idea if your fans are working? Any idea if your coolant was low from the get go?

If it were me, I would clear the snow off. I would fill it back up with coolant and make sure and burp the system to ensure there is no air in the system. When the car is up to temp, make sure the fans come on/off like they are supposed to. I would then do a compression test with the engine all nice and warm, because it may reveal head gasket damage. Then lastly if all of that is OK, I would do a cooling system pressure test. Any mechanic shop should have the equipment to pressurize your cooling system and see if it is leaking anywhere. If no problems are found. I would then drive it around awhile and make sure it's not overheating anymore. If it still is overheating, then I'd just start digging further. Maybe bad thermostat, clogged radiator, warped head, etc...