If you thought you were hot yesterday stewing in your car on the way to the beach, bent over your back yard barbecue or paddling your canoe on the Potomac, imagine how Bill Irons of Sparks, Nev., felt in his full-length Indian regalia of beads, buckskin and buffalo horns at a festival of American Indian culture on the Mall.

Definitely not dressed for the weather, Irons, a 58-year-old Hunkpape Sioux who will ride horseback in today's Fourth of July parade, nevertheless seemed surprisingly sweatless in the sweltering heat that fell on the Washington area yesterday like a huge wet rag and that will continue during today's festivities for the nation's 207th birthday.

Despite the heat, crowds in the hundreds of thousands are expected to gather today for parades, concerts and fireworks around the Washington area. Last year 350,000 people gathered on the Washington Monument Mall grounds for Independence Day celebrations, officials of the National Park Service said. Temperatures brewing in the 90s and humidity hanging in the 60 percent range made it seem that Washington had reached the epicenter of Dante's Hell.

"I thought I'd be walking, but I'm swimming right now; it's pretty moist out here," said tourist Alan Eades, 25, of San Diego as the perspiration dribbled down his shirtless chest.

Beaches and parks attracted thousands seeking relief from the heat. In Ocean City, where officials estimated the weekend brought an influx of 300,000 beachgoers, police reported "normal to above average traffic" yesterday with no major arterial clogging. But they said they expected a major traffic jam this evening as fireworks watchers converge for the show there.

Dorothy Werner, spokeswoman for the Northern Virginia Regional Park Authority, reported that the parks were overflowing with people "picnicking, swimming, boating and just sitting under shady trees." The authority's new "wave pool" that makes waves up to four feet high in Alexandria's Cameron Run Park drew "its biggest crowd this year," Werner said.

Even those who stayed indoors for cooler endeavors such as computer games were in some peril yesterday if they lived in the McLean and Great Falls area where a Vepco power outage at 4:10 p.m. stilled the hum of refrigerators and air conditioners for some 3,000 customers. Power was restored about 2 1/2 hours later, Vepco said.

The highest temperature in the region was reported at Richmond, 96 degrees. Washington and Baltimore were close behind with 94 degrees each. In Washington the humidity was 62 percent.

But the heat did not dampen enthusiasm generated by tribal dancing under a big white tent yesterday on the Mall, site of the first American Indian Heritage Festival.

The festival, which will continue through today, is organized by the American Indian Heritage Foundation to increase awareness of the American Indian's culture, said coordinator Rob Huberman. A contingent of American Indians led by the foundation's president, Princess Pale Moon, singer Wayne Newton, who is half Cherokee, and Iron Eyes Cody, who exhorts television viewers to "Keep America Beautiful," will march in today's parade.

For Irons, born on the Standing Rock Reservation in Thunderhawk, S.D., it was the first American Indian festival he had attended "east of the Missouri River." He said his mother, now 83, spent 1,800 hours making his beaded headdress and outfit by hand.

Also contributing to this story were staff writer Joanne Ostrow and special correspondent Mark Sutton.