Schools closed, a highway buckled and utilities were keeping a wary eye on high demand for electricity as a record heat wave boosts temperatures into the 90s along the East Coast.

It's little more than a week since a cold snap dusted the Appalachians with snow and nipped young vegetables in the bud. And this extreme of heat follows a winter that set new standards for cold and snow in the Northeast.

``It's still May! If summer's started right now, how hot is it going to get?'' Olga Gaouliabris said in Philadelphia, where Monday's high of 94 tied the record for the date.

``Lordy, I'm dying,'' Mable Lucas said Monday as she waited for a bus in downtown Wilmington, N.C., which tied its record at 93. ``Well, I guess it's started. We won't stop sweating until November.''

Hot, humid air surged northward, not stopping until it bumped into a cold front that stretched today from Texas into northern New York state. The front was expected to move slowly southeastward, bringing relief later today to at least some of the Northeast.

On Monday, readings in the 90s extended from Texas eastward along the Gulf Coast and northward along the East Coast.

Newark, N.J., reached 99, the hottest on record there for the entire month of May. Windsor Locks, Conn., also hit a record 99 and New York hit 96, far surpassing the old record for the date, 91.

At the opposite extreme, however, chilly air settled into the northern Rockies this morning. Casper, Wyo., cooled to a record low of 30, and Great Falls, Mont., tied its record at 31.

Many schools in North Carolina and Virginia closed early Monday because outside temperatures in the 90s made classrooms unbearable. In Pulaski, Va., the temperature rose one degree every 10 to 15 minutes in elementary school classrooms, said superintendent Wallace Saval.

Temperatures hit 96 in Delaware, heating Interstate 95 so much that the pavement expanded and buckled, creating a 4-inch dropoff in the southbound lanes near the Pennsylvania line.

Power supplies were stretched thin as fans and air conditioners were cranked up, and a consortium of power companies with customers in Maryland, Delaware, Pennsylvania and New Jersey reduced power by 5 percent.

``It's all weather-related and there are some major units off line (for maintenance or repairs),'' said Rick Hofmann, spokesman for Delmarva Power & Light Co., based in Wilmington, Del.

In New York City, Consolidated Edison Co. asked customers to use less power because outages elsewhere had reduced reserves of the state power pool.

``What's scary is the volatility of the weather,'' said vegetable farmer Irwin Sheppard of Cedarville, N.J. ``This is just a precursor to scare us.''