A heat wave baking much of the Northeast and Midwest persisted into its fourth day Thursday, aggravating a severe drought and causing at least two deaths in Boston.

Five tornadoes, meanwhile, spun through Colorado, hurling vehicles through the air and injuring seven people.Temperatures were expected to zoom again Thursday into the 90s from southern New England across eastern Virginia, as far south as the Gulf coast and as far west as Montana.

"Have you seen the movie `Good Morning Vietnam'? Robin Williams has a line in there that sums it up: `Hot, damn hot, hot and wet,"' said Frank Ackerman, spokesman for the Cape Cod National Seashore in Wellfleet, Mass.

An estimated 196,000 people jammed beaches Wednesday in the New York City area as the temperature hit 96 degrees, tying a 97-year-old record. It reached 98 in Boston, exceeding by 2 degrees the record set in 1956.

The bodies of an elderly woman and her daughter were found Thursday in their Boston apartment. A preliminary investigation indicated the women died because of the heat, said police spokeswoman Jill Reilly.

In Massachusetts and Rhode Island the miserable weather became an official heat wave, meaning at least three straight days of temperatures at 90 or higher, the National Weather Service said.

Kent County Memorial Hospital in Warwick, R.I., reported an increase of people coming in with chest pains.

"We've had a lot of chest pains, which I'm sure are precipitated by the heat," nursing supervisor Gertrude Bollengier said Thursday. She said no cases of heat exhaustion had shown up yet. Rhode Island Hospital in Providence and Newport Hospital officials reported no increase in heat-related illnesses.

The unrelenting heat prompted Rhode Island Public Transit Authority bus drivers to threaten a walkout over broken air conditioners, as highs in Providence on Wednesday reached 97 degrees, one degree below the 1945 record.

"It's more than uncomfortable," said Edward Rodgers, president of the drivers union. "It's a safety issue. What if a driver passed out? . . . It could be a catastrophe."

In Colorado, thunderstorms spawned five tornadoes in an area 55 miles long from north to south, tossing vehicles and storage sheds through the air and tearing off several roofs. Seven people were injured, none seriously.

One twister hit near Denver's Stapleton International Airport, where the air traffic control tower was evacuated for about 25 minutes, Stapleton spokesman Richard Bouleware said.

Much of the property damage involved uprooted trees, lost shingles and broken windows, rather than destruction of homes, officials said.

To the east, the severe heat is being caused by a high-pressure system off the mid-Atlantic Coast pumping in hot air from the south central part of the country, National Weather Service meteorologist Mike Wyllie said.

"Over hundreds and hundreds of miles, the ground is very, very dry," said Peter Lamb of the Illinois State Water Survey. "So what the sun is doing is heating the ground and the ground is heating the air."

The heat, coming in the wake of a dry winter and spring in the nation's midsection, aggravated widespread drought conditions that have threatened farm yields, sending prices rocketing on commodity exchanges.