Extreme heat wave reaching its peak, especially in Midwest and Gulf Coast
An ongoing monstrous heat wave is reaching its peak as more than 110 million Americans find themselves under risk from dangerous heat indexes Wednesday. Record temperatures are set to focus on the Midwest and Gulf Coast region Wednesday and Thursday, before returning mainly to the South and toward Texas by Friday and Saturday.
Excessive heat warnings are in effect for parts of 19 states, including all of Iowa, Missouri, Arkansas, Louisiana and Illinois. Areas under excessive heat warning can anticipate heat index values near and past 110 degrees, along with actual temperatures above 100.
Heat warnings are surrounded by heat advisories or heat watches on all sides. When combined, about 130 million people are under heat alerts.
“It is imperative to take the heat seriously and avoid extended time outdoors, as temperatures and heat indices will reach levels that would pose a health risk,” wrote the Weather Prediction Center. It noted that heat may be “potentially deadly to anyone without effective cooling and/or adequate hydration.”
Following another day full of record highs and record warm lows Tuesday, several hundred additional records are a good bet in days to come.
Chicago is forecast to flirt with 100 degrees both Wednesday and Thursday. If the city manages to reach that mark, it would be the first time since early July 2012. Chicago is in its third-longest streak on record without hitting 100.
Some of the record high temperatures forecast Wednesday and Thursday include:
- Shreveport, Louisiana: 107 and 107
- Mobile, Alabama: 104 and 100
- Beaumont, Texas: 102 and 106
- New Orleans: 101 and 99
- St. Louis: 101 and 103
- Memphis, Tennessee: 99 and 101
In and around Louisiana, where 100s seem to be never-ending, this next week will be punishing. New Orleans is forecast to near or pass record highs every day through Tuesday, including four days with a forecast of 100 or higher. Natchitoches, in the north-central portion of the state, is forecast to hit 110 Thursday.
Highs to 105 stretched from northern South Dakota to Central Texas on Tuesday, then eastward from there into Mississippi. Kansas, South Dakota and Nebraska saw temperatures as high as 108.
Record highs were set in the following locations, among many others:
- Salina, Kansas, with a high of 107
- Lincoln, Nebraska, with a high of 105
- Baton Rouge, with a high of 103
- Meridian, Mississippi, with a high of 102
- Minneapolis, with a high of 98
Adding in the heat index, “feels like” values of 120 to 125 were common across the Midwest, in places such as Iowa and Missouri, where extensive croplands add to the moisture in the air. This follows Lawrence, Kansas, surpassing 130 on Sunday and Monday.
Most long-term stations in Texas, Louisiana, along the northern Gulf Coast and into Florida are observing their hottest August on record, or close to it, according to the Southeast Regional Climate Center. For annual and summer tallies, it’s a similar footprint, but focused more on the Gulf Coast and Florida.
In addition to record highs, record warm lows have been falling by the hundreds, in part thanks to extreme humidity in addition to the high heat. Tuesday featured record warm lows from the Southeast to the Plains. Several cities well inland – Sioux Falls, S.D.; Omaha; Tulsa; and Memphis, among others – did not fall below 80 on Tuesday, and many probably will not Wednesday into Thursday.
Adding in the stifling humidity, plus urban heat island impacts, keeps it unbearable through the night.
“We don’t have heat indices falling meaningfully below 100 until after about 10 PM or so,” wrote the Weather Service in Chicago. Heat index values are probably “remaining in the upper 80s/near 90 for the bulk of the night.”
The low temperature Thursday might be about 80 in Chicago, which would be a record for the date. In Houston, record warm lows are forecast Thursday through at least Tuesday. The lowest temperature expected there is 80 through the stretch, with a few nights perhaps only making it to the mid-80s.
Lack of meaningful cooling at night significantly compounds health risks, especially for the poor and unhoused.
Once into the weekend, heat is probably pushed southward to focus on the Gulf Coast. By next Tuesday, only a few record highs will be at risk. History says we might watch that tally rise as Tuesday approaches.
“The trend has been as high temps in the extended (forecast) move into the mid to short term, numbers are added to them,” wrote the Weather Service in New Orleans.
It does appear that the most intense heat will shift westward to end August. Thereafter, it might shift back east during the first week of September.
The average date of the last 100-degree day for the year is Aug. 17 in El Paso, Aug. 26 in Dallas and Aug. 31 in Austin, so based on history, the days of extreme heat should be ending soon. Hot spots out west, such as Phoenix, see 100-plus highs into October during most years.