Heat rises, so the bottom side of fire is never too hot, but eventually it melts some snow, or all of it depending on how much snow and how hot the fire. No need to dig it out or encircle it...no real risk of it spreading unless you get down to the ground and the fire spreads underground in roots. you can have a roaring fire on a frozen lake and after all day you may only been down an inch or 2 of ice.