WFAA-TV

All of North Texas is under a heat advisory until 7 p.m. Monday; Dallas, Tarrant, and the other counties highlighted in red are under an Excessive Heat Warning.

DALLAS — Temperatures in North Texas are expected to exceed 100 degrees again on Monday, and the state is poised to break the all-time record for electricity use.

An Excessive Heat Warning remains in effect through 7 p.m. Three weekend deaths are being investigated as possibly related to the hot weather.

WFAA-TV meteorologist Greg Fields forecast a high of 105 degrees Monday afternoon; the record is 107, set in 1951.

Sunday's high of 107 Sunday shattered the previous record by two degrees. It was the hottest day of 2008.

North Texas averages 16 triple-digit days per year.

The electric grid operator for most of the state is asking residents and businesses to reduce afternoon electricity usage because of the extreme heat.

The Electric Reliability Council of Texas and the Public Utility Commission urged Texans to reduce their electricity use Tuesday during peak electricity hours from 3 p.m. to 7 p.m.

Kent Saathoff, ERCOT vice president of system operations, says no electricity emergencies are expected, but that the grid operator will be monitoring the situation closely.

It also helps to close all blinds and drapes and to set thermostats at 78 degrees or higher.

The Excessive Heat Warning — which includes residents of Dallas, Tarrant, Collin, Denton, Rockwall, Grayson, Fannin, Lamar, Hunt, Delta, Hopkins, Kaufman, Van Zandt and Rains counties — means that excessive heat coupled with high humidity levels make outdoor activities particularly dangerous.

The National Weather Service recommends taking frequent breaks and drinking lots of water. Wear loose-fitting and light-colored clothing.

Be sure to check on elderly neighbors and relatives or those with health problems, since they are among the most susceptible to heat exhaustion and heat stroke.

Never leave people or pets in an enclosed vehicle, even for a short time, the weather service advises, because temperatures can quickly rise to deadly levels.

The Associated Press contributed to this report.