Extreme heat warnings are in effect for areas of 19 states, including all of Iowa, Missouri, Arkansas, Louisiana and Illinois. Areas under a heat warning can expect heat index values near and above 110 degrees, along with actual temperatures above 100.
Heat warnings are surrounded by heat indicators or heat watches on all sides. Combined, about 130 million people are on heat alert.
“It is imperative that you take the heat seriously and avoid prolonged time outdoors, as temperatures and heat indices will reach health-threatening levels.” wrote the Weather Prediction Center. He noted that the heat can be “potentially fatal for anyone without effective cooling and/or adequate hydration.”
Another day full of record highs and record warm lows follows on Tuesday, several hundred additional records it's a good bet in the next few days.
Extreme heat extends eastward
Chicago is projected to flirt with 100 on both Wednesday and Thursday. If the city manages to reach that mark, it will be the first time since early July 2012. Chicago is on the third-longest streak without reaching 100.
Some of the record high temperatures forecast for Wednesday and Thursday include:
- Shreveport, La.: 107 and 107
- Mobile, Ala.: 104 and 100
- Beaumont, Tex.: 102 and 106
- New Orleans: 101 and 99
- St Louis: 101 and 103
- Memphis: 99 and 101
In and around Louisiana, where the 100s seem to never end, this next week will be punishing. New Orleans is forecast to approach or exceed record highs every day through Tuesday, including four days with a forecast of 100 or higher. Natchitoches, in the north-central part of the state, is forecast to reach 110 on Thursday.
The relentless heat breaks records
Highs up to 105 stretch from northern South Dakota to Central Texas on Tuesday, then eastward from there into Mississippi. Saw Kansas, South Dakota and Nebraska temperatures up to 108.
Record highs were set in the following locations, among many others:
- Salina, Kan., with a high of 107
- Lincoln, Neb., with a high of 105
- Baton Rouge, with a high of 103
- Meridian, Miss., with a high of 102
- Minneapolis, with a high of 98
Adding to the heat index, “feel” values of 120 to 125 were common across the Midwest, in places like Iowa and Missouri, where extensive crops add moisture to the air. That's followed by Lawrence, Kan., topping 130 on Sunday and Monday.
Most long-term stations in Texas, Louisiana, along the northern Gulf Coast, and Florida observe at or near the hottest August on record; according to the Southeast Regional Climate Center. For annual and summer tallies, it's a similar footprint, but more focused on the Gulf Coast and Florida.
In addition to record highs, record warm lows are down by hundreds, thanks in part to extreme humidity and high heat. Tuesday brought record low temperatures from the Southeast to the Plains. Many cities well inland — Sioux Falls, SD? Omaha? Tulsa? and Memphis, among others — didn't drop below 80 Tuesday, and many likely won't Wednesday through Thursday.
Add in the sweltering humidity, as well as the effects of urban heat islands, and it keeps it unbearable all night.
“We don't have heat indices drop significantly below 100 until after 10 p.m. about,” the Weather Service in Chicago wrote. Heat index values will likely “remain in the 80s/near 90s for most of the night.”
Thursday's low could be around 80 in Chicago, which would be a record for the date. In Houston, record low temperatures are forecast for Thursday through at least Tuesday. The expected low there is 80°C across the board, with some nights perhaps only reaching the mid-80s.
The lack of substantial cooling at night greatly enhances health risks, especially for the poor and homeless.
Once the weekend rolls around, the heat will likely push south to focus on the Gulf Coast. Until next Tuesday, just a few records will be in danger. History says we may watch that tally rise as Tuesday approaches.
“The trend was such high temperatures in the extended [forecast] move to medium to short term, numbers are being added,” the Weather Service in New Orleans wrote.
It looks like the hottest heat will shift westward by late August. It may then turn eastward 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 end soon. Hot spots in the west like Phoenix see 100+ highs in October most years.
