Weather forecasters this year are using the Mean Heat Index, a measure of how hot a person actually feels over the course of a day. A reading over 85 is considered dangerous, giving the public and government officials a warning that could prevent heat-related deaths.

Excessive heat claimed 219 lives last year, more than floods, tornadoes, lightning and hurricanes combined. "Heat waves kill with silence," says Jim Hoke, director of NOAA's Hydrometeorological Prediction Center in Camp Springs, Md. "Intense heat can creep up on its victims, because it doesn't have the loud, crash-and-bang of a hurricane or tornado. Its average death toll, however, is much worse."

It's not surprising that June is the peak month for shipments of central air conditioners, according to the Air-Conditioning and Refrigeration Institute (ARI), as contractors and distributors respond to increased demand for what can be life saving equipment during extreme heat.

For the first five months of 2002, ARI said factories shipped 3,035,366 central air conditioners and heat pumps, which cool in summer and heat when it is cold, an increase of six percent over the same period last year.

With shipments expected to meet or exceed 900,000 units in June, the industry by the end of 2002 will likely eclipse last year's total of 6,281,443, including a record 1,442,355 heat pumps. A new record appears likely for heat pumps in 2002 with shipments up 7 percent during the January through May period.