Flounder fishing: Hot, windless days on simmering inlets, the noonday sun broiling your nose beet-red, fitful, mosquito-plagued nights in a camper when the mercury never seems to drop into a comfortable range.

But it doesn't have to be that way: Right now you can catch bigger flounder, without the irritations of summer. May is a marvelous time to head for the protected bays and backwaters of Maryland and Virginia's eastern shores. Catches of 15 to 30 fish per boat are coming in at Chincoteague; farther south at Wachapreague, 20 to 80 flounder are being taken by charter-boat parties.

Early flounder also tend to be big flounder. The large "doormats" make an early surge in from deep wintering grounds each spring. Ten-pounders have already been weighted in a Wachapreague, and more will likely turn up during the rest of this month.

The truism "big bait, big fish" doesn't always hold in angling, but flounder fishing is one case where it's valid. Most anglers who specialize in catching flounders too big to fit in the cooler like minnows at least three inches long, preferably four or five.

Mummichogs (killies) are the easiest to obtain and prove hardiest on the hook, but some flatfish experts don't like them: John Shields, a retired state trooper from Manasas who now runs Chincoteague's Snug Harbor Marina, wouldn't be caught dead with a mummichog on his line. Frozen silverside shiners are his choice, even though they're tough to keep on the hook when they thaw and get soft. Still another alternative is a combination of a three-to four-inch tapered strip of squid draped on a hook with a minnow. This makes a chunky package that often outfishes either or silversides by themselves.

Whichever, impale your bait on a longshank No. 1/0 or 2/0 hook, which are easier to remove than short models and eliminate the need for heavy leaders, since the flounder seldom gets the entire hook in its mouth where its raspy teeth can fray the line.

A bucktail-dressed hook seems to lure more fish to the bait than a bare one. You can get them already rigged, but storebought models usually have inexcusably heavy leaders. You can tie your own with just a bit of size A red thread, white bucktail and clear cement. Simply cut a small bunch of buctail slightly longer than the hook shank and tie it in firmly just behind the eye of the hook with the thread. A dab of cement keeps the thread from unwinding.

For terminal gear, you'll need three-way swivels, sinkers and leader material. Tie a dressed hook to a 12- to 24-inch piece of 12-pound mono for your leader and knot this to a three-way swivel. On another eye of the swivel, attach a five- to ten-inch piece of line and tie on a dipsey sinker of one to three ounces. The third eyelet is for the line from your rod.

What sinker weight to use hinges on three factors - line diameter, depth of water and speed of wind and current. The best rule is to use the lightest weight you can while still keeping the minnow smack on the bottom.

Lines testing eight to 12 pounds are heavy enough for any flounder in the mid-Atlantic. Heavier mono simply impedes the action of the bait and reduces its sink-rate - meaning heavier sinkers, thicker rods and less sport. Level wind or spinning reels both work well. Rods should have a bit of backbone so that the weight of the sinker alone doesn't double them up like a limp noodle. Five- to 6 1/2-foot lenghts are about right.

Chincoteague and Wachapreague on Virginia's lower eastern shore, the Bay Bridge Tunnel near Norfolk and Sinepuxent Bay near Ocean City are the four most popular spots among Washington flounder buffs. Delaware Bay also offers good flounder chances, and if you're traveling to North Carolina, Pamlico Sound provides prime flounder prospects.

Inquiries at local bait shops and marinas for locations of specific hotspots. The best fishing almost predictably occurs near the edges of deep channels in feeder inlets close to where they join the Atlantic. If you're new to the area, see where other boats are fishing and work a polite distance away.

Drifing is the only way to go when flounder fishing. Contrary to popular opinion, flounder are very aggressive fish. They are far more likely to strike moving baits that look like injured prey trying to escape than a bait anchored firmly on the bottom. Drifting also allows you to cover more territory and find fish quickly. Make exploratory drifts with wind and tide across channels until you strike paydirt. Then drift again through any areas that produce fish until the action slows.

When a fish pecks at the bait, don't do anything. Simply pull him along for five to ten seconds as the boat drifts. If the pressure is still good and you feel him chomping away at the minnow, snap the rod up sharply and you should have a flatty plunging on the end of your pole.

Slack tides are the least productive times for flounder. The best times are an hour before and after tide changes. On a rising tide, look for fish on the edges of channels and up on the flats in cuts and drains where they venture to feed. On a falling tide, seek flounder in deeper channel waters.

Flounder are excellent for family trips - easy to catch, tasty to eat and finable without any exorbitant charter fees or long rides through rough water. You can wait until July, when the crowds and mosquitos arrive, but for bigger fish and fewer people spring is tops. CAPTION: Picture, MAYS IDEAL FOR FLOUNDER FISHING: BIGGER FISH, BETTER WEATHER, FEWER FELLOW FISHERMEN. By Angus Phillips.