At 1 p.m., thermometers were reading 100 or higher at Raleigh, Fayetteville, Lumberton, Rocky Mount and Roanoke Rapids, the National Weather Service reported.
Even the coast was hot, with 89 at Cape Hatteras and 93 in Manteo.
Asheville, which hit 92 on Wednesday, was at 89 in the early afternoon readings, the Weather Service said.
Outdoor burning is illegal during a Code Orange, and officials also urged people to limit driving to reduce air pollution.
The heat piled onto a day of high temperatures on Wednesday.
Raleigh reached a high of 102 degrees, while Rocky Mount saw 103-degree weather. Sanford, Southern Pines and Lumberton tied for a regional high of 106 degrees.
Grandfather Mountain experienced its second day of record heat, setting a new daily record high of 80 degrees.
Gov. Mike Easley urged residents to set their thermostats to between 78 and 80 degrees and ordered that at nearly all state agencies.
"This is just a small price the state can pay to help conserve energy on hot days like this," said McKinley Wooten, deputy secretary for the state Department of Administration.
Some homeowners said they're already taking additional measures to conserve energy.
"I just think, overall, we need to be more conservative with our energy – cutting up the thermostat, running ceiling fans, not using the oven anymore than we have to," homeowner Carol Bedwell said.
North Carolina Electric Cooperatives, a network that services 2.5 million customers, most of them in rural areas of the state, hit record usage at 2,967 megawatt hours around 6 p.m. That usage broke the previous record of 2,869 megawatt hours set Jan. 19, 2005, a spokeswoman said.
Earlier, the network asked customers to turn off unnecessary electronics and to use electricity and air conditioning sparingly.
"That's what everybody needs to concentrate on," agreed Carol's husband, Robert Bedwell. "When they're not using things, turn them off, TVs and so forth."
Large and small local air-conditioning repair service companies told WRAL the number of service calls they receive has increased dramatically this week.
Calls to The Service Experts tripled, from an average of less than 50 to a 115 in one day, the company reported. Smaller companies, Pillar & Sons and Ellis Heating & Air Conditioning, said their calls have jumped by between 40 and 50 percent.
The N.C. Museum of Natural Sciences in Raleigh was forced to close its doors to visitors at 1 p.m. after its air-conditioning unit malfunctioned. Museum officials said they planned to open as usual on Thursday, but suggested visitors to call ahead in the morning at 919-733-7450.
"With more people and higher heat, we have the formula for high demand," said Jane Pritchard, speaking for the cooperatives. "We're trying to be prudent."
In Knightdale, 9,200 Progress Energy customers lost power Wednesday afternoon in a blackout that officials blamed on high temperatures and high demand.
Nearly 500 Progress Energy customers also experienced sporadic outages in parts of western Cary.
Progress Energy has experienced near-record demand from its 1.2 million North Carolina customers for the past several days, and its system is being strained, said company spokeswoman Tanya Evans. Progress Energy set its previous record in July 2005.
"We are hoping to avoid brownouts or blackouts. That is probably a worst-case scenario and several steps down the road," Evans said.
Duke Energy did not ask customers for conservation but suggested that people monitor their usage. The utility missed its all-time high usage by 103 megawatts Tuesday, officials said. The all-time high of 18,687 megawatts was set on July 27, 2005.
Record demand also was a possibility for Richmond, Va.-based Dominion Power, which asked its 2 million customers in northeastern North Carolina and Virginia "to alleviate excess demand on the grid," spokesman David Botkins said.
All the utilities said they should be able to manage the spike in usage.