More than 100 million in the US face excessive warning or heat advisories as a dangerous heat wave continues

(CNN) - Heat alerts cover more than 20 states today and tomorrow across the Southern Plains and parts of the Northeast, and temperatures will soar above the century mark for 60 million people over the next week.

All while a similar heat wave is bringing all-time record temperatures to Western Europe.

"Dangerous heat will continue to impact a large portion of the US this week, with now more than 100 million people under excessive heat warnings or heat advisories," the Weather Prediction Center said.

It means one-third of the US population is under heat advisories and excessive heat warnings today and tomorrow, and more than 80% of the US population (around 265 million Americans) will see a high above 90 degrees over the next seven days.

The highest temperatures, pushing well into the triple digits, will be once again centered over the southern Plains.

More than two dozen record highs are possible today and tomorrow for the Southern US, including Texas, Oklahoma, and New Mexico, and the East Coast is about to get into the mix as well.

Parts of the Northeast will also have temperatures nearing daily records Wednesday and Thursday.

"Heat advisories are also now in effect for Wednesday for portions of the Northeast, including the I-95 corridor from Philadelphia to Boston, where heat index values are forecast to reach near 100 degrees," the Weather Prediction Center said.

The southern Plains are given another dose of intense heat

After a record-breaking heat day yesterday, the southern Plains are being met with dangerous heat once again.

Dallas inched toward its daily record of 110 degrees yesterday but topped out at 109, making it the hottest day of the year so far.

But today will be worse.

Temperatures are forecast to reach 111 degrees in the area, crushing the daily record of 108.

The oppressive heat has strained the Texas power grid, as the state expects another day of record energy demand.

Excessive heat warnings and heat advisories are in effect through Wednesday for North and Central Texas.

"The air temperatures will climb to 105 to 110 degrees in the warning area, with heat index values over 105 degrees in the advisory area," the National Weather Service in Fort Worth said.

As hot temperatures, low humidity, and wind speeds pick up, a critical fire danger threat is also in effect for northern Texas and central Oklahoma.

Oklahoma City could see highs nearing 110 degrees today, which would break their daily record of 109 set back in 1936.

"The last time we had a substantial stretch of heat was in 2011, when we had 63 days greater than or equal to 100 degrees," Vivek Mahale, a Norman National Weather Service meteorologist, said.

Mahale expects the above-average heat to continue into at least Sunday, with every day reaching the triple-digit mark.

The Oklahoma City Will Rogers World Airport has seen nine days above 100 degrees this month.

He advised the best thing you can do to prepare is to check on vulnerable populations as temperatures will be five to seven degrees above normal.

"We really want to emphasize you want to check on your friends, family, and neighbors during the heatwave, especially susceptible populations such as the elderly," Mahale said.

Farther north, Michigan's Occupational Safety and Health Administration encouraged employers to be aware of heat hazards and help prevent heat illness.

"Whether you're working indoors or outdoors, hot and humid conditions can pose serious risks to workers' health, but heat-related illnesses are preventable," Michigan's Occupational Safety and Health Administration Director Bart Pickelman said in a news release.

Employers, it said, should have detailed procedures in place for monitoring the heat index, provisioning water and caring for a sick employee, it said.

New York, Boston and Philadelphia brace for sweltering week ahead

Heat advisories are in effect tomorrow for the Northeast, including New York City, Boston, and Philadelphia.

"Oppressive heat and humidity returns this week," the Boston National Weather Service tweeted.

Heat index values -- the temperature it feels like when heat is combined with humidity -- could top 100 degrees in some areas, generating dangerous conditions for Mid-Atlantic and New England residents.

The heat and humidity won't just hug the coast. Upstate New York could also see temperatures well above average.

Albany, New York is soaring above their average of 84 degrees for this time of year, and the city could near their record of 97 degrees tomorrow with the stifling heat.

To make matters worse, humidity combined with heat will make some areas feel 5-10 degrees hotter.

"This is going to be little bit (warmer) than just the typical hot and humid weather that we get in July," Mike Evans, a meteorologist at the National Weather Service office in Albany, New York, told CNN.

Evans said dew points could push 70 degrees tomorrow, which is when humidity becomes "very noticeable."

Portions of Massachusetts will reach record levels as soon as Wednesday, as temperatures reach the upper 90s, and will continue through the rest of the week in the Northeast.

"This is going to be the hottest day we've had so far, this summer. We really haven't had too hot of a summer here, at least in the Northeast," Evans said.

The US isn't likely to see much relief over the next week. The Climate Prediction Center forecasts above average temperatures will likely last well into next week for most of the lower 48.