The Electric Reliability Council of Texas broke a new peak power demand set the day before.
Electric use on Tuesday from 4 - 5 p.m. reached 66,583 megawatts in San Antonio.
The record broke the one previously set on Monday of 65,047 megawatts.
ERCOT's all-time peak demand record occurred on August 3, 2011, when electric use topped 68,379 megawatts.
Cities across the state were again baking in triple-digit heat, a year after Texas endured the second hottest summer in U.S. history in a three-month stretch that forced multiple warnings for an overburdened energy grid.
Though temperatures were expected to dip back into the 90s late in the week, officials acknowledge more conservation will be needed for the next couple months if they are to handle electricity demand from most of the state's 25 million residents.
"Summer is here in full swing," said Robbie Searcy, a spokeswoman with the Electric Reliability Council of Texas.
The record-breaking temperatures were felt in Austin at 109 degrees, Houston at 105 and Victoria at 108. This prompted heavy power usage across the state as Texans tried to stay cool. ERCOT estimated statewide usage surpassed 66,500 megawatts for the first time this year Tuesday — a record for June and July. The number eclipsed a June record set Monday of 65,000 megawatts.
Although ERCOT predicted it would not need an emergency alert this week, the grid operator encouraged Texans to conserve energy by setting their air conditioners two to three degrees higher during peak consumption hours.
CPS Energy advises residents to try to set their thermostats at 78 degrees or higher during peak hours if they can tolerate it.
The National Weather Service has offered one bit of good news for those struggling to endure the heat: Summer 2012 won't approach last year's scorching heat, though it will be a couple degrees higher than normal. Statewide average temperatures typically hover in the low 80s; last July-August the state averaged 86.5 degrees.
Tips for coping with the heat in San Antonio
The Salvation Army has four cooling centers opened including the Family Emergency Shelter at 515 W. Elmira and Dave Coy Shelter at 226 Nolan that are open 24 hours.
The city of San Antonio has 41 designated cooling centers, which are listed here. The locations are open during regular hours but if high temperatures continue, the city may extend some of the times.
Prolonged exposure to the heat may lead to heat exhaustion and heat stroke.
Experts say to take extra precautions if you work or spend time outside.
When possible, reschedule strenuous activities to early morning or evening.
Know the signs and symptoms of heat exhaustion and heat stroke.
Wear light weight and loose fitting clothing when possible and drink plenty of water.
To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air-conditioned environments.
Anyone overcome by heat should be moved to a cool and shaded location.