From Midwest Energy...
If your furnace isn't working well, it might be snow around your gas meter or your vents. A blocked pressure regulator vent on your gas meter can cause your meter to stop working. Just remove snow from a few feet from your meter with a broom (don't go digging on it with a shovel and damage the meter face!), and you're all set.
Also... if your furnace vents are on the side of your home (and not the roof), check to see that they're not blocked by drifted snow or ice. Either condition can cause your furnace to shut off, or if still running can allow carbon monoxide to build up in the home. Please take a moment to ensure your family will be warm and safe tonight! Thanks!