It's time to treat your door locks if you expect very cold weather. Water gets inside, and the very cold weather can freeze the lock. Think ahead.
There are various methods, and which methods are good and proper can get heated. My current method is to squirt antifreeze in with a basketball inflation needle that is taped to a big dropper. I plan to follow that up in a day or two with some very light oil. My theory is that some water gets washed away, and some gets mixed with a lot of antifreeze. The oil is because the antifreeze would wash away lubricant. It seems to work for me.
Those who propose to use silicon spray seem to have a very good presentation. There are proponents of WD-40. There are little containers of fluid that are sold for the purpose; they seem to be the most expensive method.
So I won't say you should use my method. I won't be offended by those who post that my method is the worst way. Just don't find yourself locked out Jan 2 because you forgot to take whichever action you deem proper.