Spring: clear gutters and downspouts, check exterior cracks and peeling paint, test smoke/CO alarms, clear debris around AC condenser.
Summer: check door/window seals, clean dehumidifier/AC filters, inspect basement for moisture or musty smell, trim branches near the house.
Fall: drain outdoor faucets and shut interior valves, test heat/heat pump, check chimney and vents, prep snow tools and salt.
Winter: keep steady indoor heat to avoid frozen pipes, clear roof snow safely (or hire pros), check sump pump and backup battery.