Heat and humidity can take the wind out of the sails of even the most industrious homeowner, and there are a lot of important chores to do before the dog days of summer.

If you have central air conditioning, you should have a technician perform a checkup. At least replace the filter. While the technician is visiting, you might as well have the furnace checked, so a return visit will not be necessary in the fall.

If you need a window air conditioner, measure the square footage of your room. If, for example, the room is 100 to 150 square feet, not very sunny, and not a kitchen, 5,000 BTUs will work, according to U.S. Department of Energy calculations. If the room is sunny, buy 5,500 BTUs. If it's sunny and a kitchen, you will likely need 9,500 BTUs.

If you already have window air conditioners, get them out of storage. Plug them in to make sure they work properly, and clean the filters, following the manufacturer's instructions. This typically involves vacuuming the condenser coil and the filter, washing the filter with warm water and a mild detergent, and letting the filter dry thoroughly.

When you install an air conditioner, position it so that the water from condensation does not drain into the windowsill. There should be a drain hole just below the condenser coil. You might be able to insert a hose into the hole to help redirect the water safely.

Seal the opening around the unit so you do not lose the cooler air and let the bugs in.

Most basements cannot handle the summer without a dehumidifier; they come in sizes ranging from 30 pints to 65 pints. According to the Association of Home Appliance Manufacturers, a moderately damp, 1,500-square-foot basement area should have a dehumidifier capable of removing 18 pints of water from the air every 24 hours. Buy an energy-efficient model that allows you to set the humidistat to the desired humidity level, and make sure you empty it when it is full. Many can be drained directly into the sump with a hose, so you will not have to worry.

Do not forget about your ceiling fans. Remove the dust that accumulated on the blades when they were not being used, because it can fly through the warm summer air. And the weight of dirt can make a fan wobble.

A ceiling fan is economical to operate and will help move the air. You can even install one outdoors, above a porch or deck, to ease the heat and annoy the mosquitoes.

This also would be a good time to wash your windows, and clean and repair screens on windows and doors.

Now that you have somewhere to escape the heat, tackle some outdoor projects.

These fall into three categories: timesavers, entertaining, and maintenance-beautification.

A timesaver: Install an automatic watering system. This can be as complicated as putting in an underground sprinkler system or as simple as adding a timer to the outdoor spigot, then hooking up a hose and an above-ground sprinkler to water the garden or lawn.

There are too many variables involved in an underground system to be covered here. You might want to hire a professional to do that job anyway, since it involves a lot of digging and measuring.

Above-ground drip-irrigation systems, however, are easier and efficient, and are especially good for vegetable gardens that will need to be watered during long stretches of vacation in the summer heat.

There are dozens of Web sites to consult, and home and garden centers usually have several varieties available to inspect up close.

Need a garden to water? Now is the time to start one.

Pick a sunny spot, or, if you are short on sun, choose plants that thrive in full or partial shade. Any basic gardening book will provide lists of both.

Need borders? Try cedar, brick, Belgian block or stone. A large stone or two with the borders, surrounded by small plants, adds a nice accent. So does a fence or trellis. You may want to install factory-made varieties or build either from scratch.

Use plenty of mulch in the garden to keep down weeds and hold in moisture. Try to find mulch that is relatively insect-free, especially if the garden is close to outdoor areas that are used regularly for entertaining.

Get the lawn in shape before the summer heat. You are running up against the time limit for reseeding, since it takes almost two weeks for many types of grass seed to germinate.

Cool-season turf grasses work best in this area. They grow well in spring and fall, becoming semi-dormant in hot, dry summer weather.

These are, in order of preference, Kentucky bluegrass, rough bluegrass, perennial ryegrasses, fine fescues, tall fescues, and bent grasses. Kentucky bluegrass is the premium lawn grass for the mid-Atlantic region. It is highly resistant to disease, but high-maintenance.

Speaking of maintenance, if you have not tuned your mower, do it now. Change the oil, sharpen or replace the blade, and replace the spark plug. You also might want to switch to an electric or battery-operated mower.

If you are planning a lot of summer entertaining, it is time to clean and seal the deck. Choose a cloudy day so that whatever cleaner you use will have time to work before it evaporates. Wear gloves and a mask, and cover any foliage to protect it from splashes. Do any repairs or replace loose or popped fasteners before you start cleaning. Tighten bolts.

Try to pick two rain-free days to seal the deck. Follow the manufacturer's directions, but you probably will need 24 hours of drying time between coats. Some sealers contain paraffin. Too much can make the surface slippery, so apply nice, even, thin coats.

Whether touching up or tackling a large-scale project, make sure you paint on days when the humidity is relatively low and the winds are light. Humidity and wind affect drying time, and if conditions are not right, you may need to repaint sooner. Never paint in direct sunlight, either. If you have a lot of painting to do, but conditions are not right, it may be an ideal time for prepping -- scraping, sanding, repairing and caulking. When that good day comes along, you will be ready.

Finally, this might be a good time to put a little more light on the subject.

Low-voltage lighting is easy to install, whether on a deck or below-ground. It also uses little energy.

If you prefer no-cost energy, try solar-powered lights. No wiring is involved, and, depending on the location of the lights, they will even operate in winter.

You could probably work them into your Christmas decorations.

After all, that holiday is less than seven months away.