If you will be spending a lot of time indoors in the winter, makes sense to clean the house thoroughly before winter actually sets in. That includes vacuuming, perhaps using a cleaner on the carpet, dusting, cleaning out the fridge and freezer, cleaning out the cupboards and finishing off any kitchen spruce-ups that got way-laid over the summer. It's also a good idea to check the house out for potential problems like shingles that could come off in a storm, leaks and other structural defects that need repair.
Here's a checklist that might help for the structural stuff, and here's a list of the fall cleaning chores worth considering before cold weather comes.
Both cleaning and inspecting would be good for your BOL, if you have one. And if you have elderly or infirm neighbors or relatives, now's the time to offer to help with these chores as well.