What's Behind the Scorching Record Heat?

Record high temperatures were set across the Midwest and South this past weekend, caused by a so-called high-pressure ridge that bottled up heat over much of the country.

Temperatures set records in many cities over the weekend, including Houston, which recorded an all-time June record of 105 degrees Fahrenheit (40.5 degrees Celsius) on Sunday (June 5). In total, more than two dozen record highs were posted on Sunday, the Weather Channel reported.

Add the heat wave to this year's extreme weather, which has included a historic tornado season (and an active hurricane season has been forecast).

The high-pressure ridge that contributed to these boiling temperatures is essentially a long area of high atmospheric pressure. These often contain dry air, and block clouds and rain.

"A lot of warm, dry air in the ridge makes it very easy to heat the air at the surface," said Jim Moser, a meteorologist with the National Weather Service (NWS) in Nashville, Tenn, a city that also set a temperature record on Sunday of 97 degrees F (36 degrees C).

These ridges are typical during the summer, but "it just happened to happen a little bit early this time," said John Lake, a meteorologist with the NWS in Fort Worth, Texas.

Houston's record-setting day was the earliest 100-degree day in the state's history, and the first few days of June have been extremely hot elsewhere, with some heat-related health issues. In Nashville, temperatures have been cooling in the evening, so the NWS hasn't issued a heat advisory there, but the daytime heat should linger into this week, Moser told OurAmazingPlanet.

"The upper air pattern that controls this is sometimes slow to change," Moser said, which keeps new weather patterns from moving in and pushing the ridge along.

Other cities that set daily records Sunday included:

• Waco, Texas 101 degrees F (38 degrees C)
• Colorado Springs, Colo. - 92 degrees F (33 degrees C)
• Nashville, Tenn. 97 degrees F (36 degrees C)
• Baton Rouge, La. 99 degrees F (37 degrees C)
• Hattiesburg, Miss. - 102 degrees F (39 degrees C)
• Ft. Smith, Ark. - 98 degrees F (36.6 degrees C)

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Reach OurAmazingPlanet staff writer Brett Israel at bisrael@techmedianetwork.com. Follow him on Twitter @btisrael.