The rustling noise you hear is a thousand Washington hostesses preparing to move their parties outside. From now until the end of September the buzz at dinner parties will be provided by bees, the glow will be moonlight and the standard disaster an unpredicted rainstorm. And the food, often as not, will be cooked on a grill.

And, often as not, the host will have forgotten to buy either charcoal or the liquid you splash onto charcoal to make it ignite and there will be a frantic phone call to someone or other, who will arrive late lugging a bag of briquets. Then, and only then, will the fire be lit. In an hour or so, the coals will have turned a powdery white and any guests not already dead of hunger will be encouraged to gather round the smoking grill while the host or hostess pokes and prods the bits of meat.

Eating out requires different preparations from eating in.

Before you sink into the lassitude of summer, do the following:

Clean the grill so that the current dinner won't taste of charred bits of a former meal. Lay in a large supply of both charcoal and charcoal starter and tack up a big note somewhere in the kitchen, a reminder to light the fire. Poke through the kitchen drawers until you locate the long-handled fork and basting brush, which have a way of vanishing over the winter. If you can't find them in the kitchen, you probably stuck them out in the garage. If you still can't find them, buy more. A kitchen fork is no use at all for shifting things around on a hot fire.

Buy bug spray and use it about an hour before guests arrive. Put out sticks of punk or citronella candles to discourage any bug-survivors from joining the party. Do not waste your money on an electronic bug killer since it takes an extremely hardy digestion to enjoy a meal eaten to the zap-zap-zap of a bevy of bugs meeting their maker.

Ordinary candles blow out in even a light wind, so instead stock up on hurricane lamps, votive candles and kerosene lamps. Use the kerosene lamps to light the table; they give a brighter light and guests do need to see what they're eating. Dot the others around the garden (being careful not to scorch any plants) because the effect is pretty and romantic. When the wax runs out or the wicks disappear, drop food-warmer candles into the holders. And lay in a supply of long, fireplace matches so that you won't spend the summer nursing burnt fingers.

Chances are your porch furniture has gotten ratty. Repaint it now, because if you wait until you have a party scheduled, it will rain, or the humidity will be so high that the paint won't dry. This is also the time to throw away any garden chairs that have developed a terminal wiggle and any that are so uncomfortable that anyone sitting on them is miserable.

Unless you can afford a tent -- and they are not cheap -- don't make the mistake of using the summer season to invite the hordes who won't fit inside your house in the winter. Sure as shooting, it will rain and though you can name a rain date, you are bound to be stuck with at least some foods that will spoil. You can't freeze everything and why go to the effort of preparing a party twice?

If your budget doesn't run to outdoor furniture, stage a picnic. Spread tablecloths on the grass, spread food on the tablecloths and spread your guests around the food. Picnics don't have to be in the countryside to be fun. Cover the lawn with several Indian print cotton bedspreads, anchor them with votive candles and in the center have a bottle of flavored vodka chilling in an ice bucket. Next to that, place a bowl of caviar, crackers and wedges of lemon. Nothing else, except, perhaps, a bowl of unhulled strawberries. Expensive, but completely simple. No silverware, no plates and no chairs.

And if you were to schedule this outdoor banquet for a night when the moon was full and put tapes of Jean-Pierre Rampal or James Galway flute music into a small cassette (which you then tucked away behind a tree), your guests would believe that they had landed in Arcadia.

When it works, outdoor entertaining is worth all the extra effort as the soft night air, candles winking like fireflies, and the path of the moon make all your guests prettier and wittier than they've ever been before.