For those with 90% efficient furnaces or water heaters and/or tank-less water heaters periodically check your exhaust vents on the side of your house for excess condensation or ice buildup. This can be dangerous. Do what you must to keep them clear but remember, things get very brittle in extreme cold.
Check your furnace filter. If your furnace won’t turn off or it is overheating and turning off too early, it may be an old filter. If you can’t get to store and replace it, you can run the furnace without it for a day or two. Additionally, don’t by one that restricts flow too much.
If you haven’t done so already disconnect any hoses connected to the spickets outside.