Ultra high efficiency furnace problem:

Do you have a ultra high efficiency furnace?  Even in lite-snow (or even no-snow), watch your furnaces combustion intake for signs of freezing over - your furnace has to “breath” in order to operate correctly!  Ice and snow can plug up the intake, causing the furnace to shut down and lock-out, especially during sub-freezing temperatures!  Keep an eye on it and clean on a regular basis - humid, moist air, mixing with hot exhaust from the furnace, can cause it to freeze-up!