The days get shorter; there's an occasional nip in the air. Thoughts turn away from vacations and summer fun toward school activities and football games. Soon leaves will start turning colors and drifting away. And no matter how much you try, you can't quite block out the notion that winter's on its way.

This is the time to take steps to minimize the impact of fall and winter on your home. Some early preparation now can help you get through those frigid days ahead and will also help you be ready for the guests and festivities those seasons bring.Take some time now to give your home a four-star fall checkup. The following suggestions are offered by experts at the U.S. Department of Housing and Urban Development; Sears HomeCentral; the Plumbing, Heating and Cooling Information Bureau and the National Association of Independent Insurers:

* EXTERIOR

The roof of your house generally receives the hardest wear of any part of the structure. It suffers wear and tear from beating rain and snow, wind, hot sun and alternate freezing and thawing temperatures.

Any point where the roof intersects with other surfaces, such as walls, chimneys and dormers, are subject to leaks; as are valleys - the places where two roof slopes intersect. Flashing materials - usually made of galvanized sheet iron, copper, aluminum, zinc alloy or flashing felt - provide protection from water penetration in these areas.

To inspect your roof, ask yourself these questions:

Is it more than 10 years old? Age can be an indication of potential problems, but remember than harsh weather can age a roof before its time. Do you notice any loose or missing shingles? Do you have water stains on interior walls or ceilings? Is there damaged flashing between the roof line and exterior walls or in any of the valleys? Are there cracked, curled or rotted shingles?

A yes answer to any of these questions can indicate a need for attention.

Then move on to windows. Wooden windows tend to swell and shrink with climate changes. Check the glazing that holds window panes and replace it when necessary. Replace broken glass panes promptly. If windows have been painted shut, they should be freed by an experienced workman to avoid damaging the frame and breaking the glass. Is it time to replace old windows? Ask yourself these questions:

Do they leak drafts of cold air? Do they give your home a neat, well-maintained look? Do they enhance your home's style? Are they easy to clean? Do they provide the right amount of light and air? Are they energy efficient.

A no answer to any of these questions could indicate a need for new windows. Quality windows can usually be installed quickly and easily.

Exterior finishes wear at different rates. Natural finishes need renewing every year or two by applying a fresh, penetrating coat when wear begins to show. Stain finishes are very durable and should last as long as five years.

It is good to paint only after most of the old film has weathered away. If paint is applied too often, coating thickness can build up to a point where it requires costly removal. When repainting, use the type of paint originally applied if it can be determined.

If you have siding, look for missing corner pieces. Have sliding slats warped or pulled away from the house? Are there dents or abrasions? If so, siding may need to be replaced.

* ELECTRICAL SYSTEMS

The wiring in most homes built today is adequate for appliances in common use. Before you install large appliances, however, check with an electrical contractor to see if additional wiring is needed.

In older homes, especially, it is important to check your home's wiring system regularly. Some things to consider:

Weatherproof. If you have outdoor outlets that are submerged in rainfall or snow, make sure they are extra-weatherproofed.

Upgrade to a circuit breaker box from an older fuse box. The circuit breaker box is safer and more convenient. Consider an upgrade of electrical service at the same time. The 100 amp service found in many homes is insufficient for microwave, computer, stereo and other large appliances.

Add Ground Fault Circuit Interrupter (GFCI) circuit breakers. They automatically shut off power in case of a short, as regular circuit breakers do, and they also provide ground-fault protection for circuits with outlets, as well as for larger loads like hot tubs and spas.

Test circuit breakers once a month. Press the test button located on the breaker to make sure it trips, or turns off the power. Remember to reset the breaker by moving the handle to off and then back to on.

Install Ground Fault Interrupter (GFI) receptacles in the bath, kitchen and basement to prevent electrocution. They combine the function of a regular outlet with ground-fault protection.

* FURNACE

Today's heating systems are quieter, more sophisticated and more dependable than ever before. But that doesn't mean they don't need regular maintenance. Utility companies and fire departments recommended that furnaces be inspected once a year to look for signs of wear and tear.

A furnace check by a trained specialist should include an inspection of all moving parts, a test run and a change of air filters. He should also test all safety circuits for proper function, inspect all wiring for loose or deteriorated connections, check ventilation and, for gas systems, confirm that ignition and burning mechanisms work accurately.

There are some things homeowners should also be aware of. Check the flame in the furnace. It should be steady and mostly blue. A yellow or wavy flame is a sign of malfunction and is dangerous. Look for discoloration or soot around the vest, which is another sign of furnace malfunction. Unusual noises should also be checked out. And be aware if the heat from the duct seems exceptionally hot or cool. Should you smell gas, burning rubber or anything else unusual, turn the furnace off and call your contractor.

Rust, corrosion, holes, gaps, debris and blockages in the flue system can interfere with the proper release of combustion gases to the outside of your home.

There will always be an odor when the furnace is first turned on; this is the dust and dirt burning off that has accumulated over the summer.

* PLUMBING

Most water pipe damage to homes occurs in January and February. Much of it could have been prevented in September and October with a few preventive measures:

- Seal cracks and holes in walls near water pipes to keep cold from seeping into the house.

- Insulate pipes in attics, basements and crawl spaces with foam rubber or fiberglass sleeves. Electric heating cables and tapes can also be effective, but be sure you follow directions carefully so you don't create a fire hazard.

- Outdoor pipes are the most likely to burst due to direct contact with cold temperatures, frost, ice and snow. Be sure to insulate these pipes with 1- to 2-inch insulation - the thicker the better.

- Put your hose away for the winter. Hoses can create places for cold to seep into your inside and outside pipes.

After you complete your fall checkup decide what if any work needs to be done and which will require the help of specialists. Never attempt structural changes or repairs of operating equipment, electrical systems or plumbing unless you know what you are doing.

But a little care and attention now can get you through the cold and snowy months ahead.