Hot pavement can compound minor tire problems, so check your tires for small tears or defects. Switch to motor oil with heavier viscosity. Check the air conditioning system for leaks. Hot weather can shorten the life of a car's battery, so weak or old batteries should be tested and replaced if necessary. Again, make sure your car's battery is in proper order.
Cold weather can compound battery problems.
Switch to heavy tread tires before the roads are covered with ice and snow. The engine oil, radiator, tires and ignition system must be in top condition to perform in cold weather. The wipers, brakes, tires and exterior lights also should be inspected. Ideally, this should be done by a certified technician. Prepare a winter kit for your car including a flashlight, ice scrapers, blankets, booster cables, flares, a large bag of salt or sand for traction, warm clothing and a small shovel.