Heat Wave to Persist in South through Friday

A dangerous heat wave that blasted onto the scene prior to the middle of June will continue through Friday, June 26, in the South.

While the late spring and summer is typically a hot and humid time of the year in the South, the heat wave has been responsible for temperatures reaching 5-15 degrees Fahrenheit above average for more than a week.

In many cases, the temperature has reached the middle 90s to 100 F on multiple days during the pattern, and more dangerous heat is on the way this week.

The combination of sunshine, excessive heat, high humidity, light winds and other conditions will push AccuWeather RealFeel® Temperatures to between 100 and 115 degrees Fahrenheit in many areas from the late morning through the afternoon hours.

According to AccuWeather Chief Meteorologist Elliot Abrams, the pattern has challenged and broken record highs, some in the books for more than 100 years.

"More long-standing records will be challenged and broken this week with highs in the 90s to near 100 F most days," Abrams said.  For example, Gainesville, Florida on average has 17 days of 90 F or above weather in the month of June and had already recorded 18 days by June 22nd.  The heat wave is being produced by high pressure at multiple levels of the atmosphere combined with intense June sunshine and dry ground.

In some cases, the heat is being magnified by below-average rainfall during May and June. When the soil is dry, more of the sun's energy goes into heating the ground, which in turn heats the lower atmosphere. When the soil is wet, more of the sun's energy is used up in evaporating moisture from the soil, rather than heating it. A moist ground helps to keep the lower atmosphere cool through the evaporation process.

During the latter part of the week and into the weekend, the coverage of storms and rainfall will gradually ramp up. The uptick in storms and cooling in the upper atmosphere will work to begin easing the extreme heat during the latter days of the week and this weekend.

According to AccuWeather Chief Long-Range Meteorologist Paul Pastelok, "A pattern change will send cooler air into the Eastern states and cause heat to build in the West toward the end of June into early July."

Temperatures are forecast to peak within a few degrees of average levels during most days next week and into the first week of July.

By Alex Sosnowski, AccuWeather.com Senior Meteorologist