(USA TODAY) - When the sun finally fell Tuesday, 108 cities across the country had set record highs for the day. By sundown Wednesday, expect another round of records to fall.

Jon Rowe, senior meteorologist at The Weather Channel, said the blistering heat wave blanketing most of the Midwest and Mid-Atlantic will continue at least through the weekend.

"There's going to be a lot of records again today. Probably again tomorrow, probably Friday, maybe Saturday," Rowe said.

The severity of the heat wave can be seen in the number of warnings issued by the National Weather Service. By midday Wednesday, the service had given every county in Iowa, Missouri, Illinois, Indiana and Ohio either a heat advisory or a severe heat warning.

After June's scorching start to the summer, Illinois is now on pace for the hottest year in recorded history. Illinois State Climatologist Jim Angel wrote on his blog that every month so far this year has been above average, and the statewide average temperature of 52.8 over those six months is the hottest on record. The previous record was a statewide average temperature of 52.1 in 1921.

The heat has sent more people to the hospital as they struggle to adjust to such an early start of the dog days of summer. In Springfield, Mo., Mercy Hospital received its first 2011 heat-related illness on June 14. This year, the first case walked in June 4, and the hospital has seen 24 more people come in with heat-related illnesses.

"It's hard on a holiday to tell people, 'Don't be drinking a bunch of soda or alcohol,' but you need to be careful about that sort of thing," Mercy Hospital spokeswoman Sonya Kullmann said. "The people who've been coming in, they haven't been drinking enough water or sports drinks."

The heat also has been hard for crews trying to restore power from the weekend storm that tore through Maryland, Virginia and Washington, D.C.

Clay Anderson, spokesman for PEPCO, which provides power to Washington and its Maryland suburbs, said crews had restored power to 89% of people who lost it in the storm, leaving 47,350 homes without electricity Wednesday morning. He said the work has been especially tough for crews from PEPCO - and assisting teams from Canada, Missouri and Florida - as they've battled blazing heat during the day and hot, humid conditions at night.

The utility has repeatedly warned all workers to abide by strict safety guidelines, which mandate sleep between shifts and plenty of breaks during the day and water throughout.

"Sometimes our customers don't understand when folks are sitting next to their truck and wondering, 'Why aren't they working?' " Anderson said. "They are working. Give them the opportunity to be safe so that their limbs don't cramp and they continue to do their job safely and efficiently."

The heat could start subsiding by Sunday. Rowe said a more regular summer pattern should settle in at the end of the weekend.

"It's still going to be horrific, but a little more average," he said.