Most fall weather-related maintenance involves preparing the house for cooler temperatures and rain or snow. Start with the roof. Has tree growth caused any branches to overhang? These can create shady, damp areas on the roof that contribute to moss or mildew growth, and can damage roof surfaces in windy weather. Prune the branches as necessary. (If the tree variety shouldn't be pruned in the fall and the situation isn't urgent, mark the task down so that you remember next spring.)
Check roof vents and the vents in the soffit, the flat area under the eaves where the roof overhangs the house, to ensure that they're free of debris, and check that flashings and chimneys are in good shape. Also watch gutters and downspouts on a rainy day to make sure they're ready for heavy rains or snowmelt. Splash blocks or downspout extensions should be positioned so that water runs away from the house without wearing away the soil under the downspout.
This is the time to remove window air conditioners and to install storm windows. Weatherproof doors, windows, vents, and any other potential air-leak sites on the house exterior.
Have heating systems, including ductwork, chimneys, and appliances, serviced and/or cleaned professionally. Winterize exterior faucets if they're not frost-proof, and insulate interior pipes if any are vulnerable to freezing. Test exterior GFCI outlets to ensure that they're ready for vehicle block-heater use if necessary in your area, or for holiday lights. Clean, oil, and store gardening tools for the winter, and service or prepare any snow removal tools.
Check any culverts or drains on your property to make sure they're not blocked, and protect tender shrubs and trees for winter. If you have a wood-burning stove or fireplace, make sure you're well stocked with firewood.