Winter checklist
Check the battery (cold stresses it), winter tires (mandatory in some regions), antifreeze washer fluid, lighting, and heating system.
Summer checklist
Check air conditioning, coolant level, tire pressure (increases with heat), windshield wipers, and have brakes checked before holiday trips.
Spring checklist
After winter: wash the underbody to remove salt, check shock absorbers, inspect filters (air, cabin), and check summer tires before mounting them.