Excessive heat warnings are in effect for parts of 19 states, including all of Iowa, Missouri, Arkansas, Louisiana and Illinois. Areas under heat warnings can anticipate heat index values near and past 110 degrees along with actual temperatures above 100.
Heat warnings are surrounded by heat indicators or heat watches on all sides. Altogether, around 130 million people are under heat alert.
“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,” the Weather Prediction Center wrote. It noted that heat can be “potentially fatal to anyone without effective cooling and/or adequate hydration.”
After another day full of record highs and record lows on Tuesday, several hundred more records are a good bet in the coming days.
Extreme heat expands to the east
Chicago is expected to flirt with 100 on both Wednesday and Thursday. If it manages to reach that mark, it would be the first since early July 2012, which is the third-longest streak ever without hitting 100 there.
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 endless, this next week will be punishing. New Orleans is expected to approach or pass 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 expected to hit 110 Thursday.
Relentless heat continues to break records
Highs to 105 stretched from northern South Dakota to central Texas on Tuesday and then east from there into Mississippi. Kansas, South Dakota and Nebraska saw temperatures as high as 108.
Record highs were set at the following locations, among many others:
- Salina, Kan., with a high of 107
- Lincoln, Neb., with a high of 105
- Baton Rouge, with an elevation of 103
- Meridian, Miss., with a high of 102
- Minneapolis, with an elevation of 98
Adding in the heat index, “it feels like” values of 120 to 125 were common throughout the Midwest, in places like Iowa and Missouri, where extensive cropland adds moisture to the air. This follows Lawrence, Kan., surpassing 130 on Sunday and Monday.
Most long-term stations in Texas, Louisiana, along the northern Gulf Coast and into Florida are observing their warmest August on record, or close to it, according to the Southeast Regional Climate Center. For annual and summer inventories, it’s a similar footprint, but focused more on the Gulf Coast and Florida.
In addition to record highs, record-warm lows have dropped by the hundreds, thanks in part to extreme humidity in addition to the high heat. Tuesday offered a record warm low from the southeast to the plains. Several cities far inland — Sioux Falls, Omaha, Tulsa and Memphis, among others — did not drop below 80 on Tuesday, and many likely won’t Wednesday into Thursday.
Adding the stifling humidity plus urban heat island effects keep it unbearable all night.
“We don’t have heat indexes drop meaningfully below 100 until after about 10:00 p.m. or so,” the Weather Service in Chicago wrote. Heat index values are likely to “remain in the upper 80s/near 90 for most of the night.”
The low temperature Thursday could be around 80 degrees in Chicago, which would be a record for the date. In Houston, record low temperatures are predicted from Thursday to at least Tuesday. The low expected there is 80 degrees through the stretch, with a few nights that might not reach the mid-80s.
Lack of meaningful cooling at night significantly exacerbates health risks, especially for the poor and homeless.
Sometime this weekend, the heat is likely to push south to focus on the Gulf Coast. Next Tuesday, only a few record highs will be at risk. History says we may see that number rise as Tuesday approaches.
“The trend has been such high temperatures in the extended movement into the medium to short term, numbers are added to them,” the Weather Service in New Orleans wrote.
It appears that the most intense heat will shift westward toward the end of August. Then it may move back east during the first week of September.
In the current climate, the average last 100-degree day comes on Aug. 17 in El Paso, Aug. 26 in Dallas, and Aug. 31 in Austin, so time is at least historically tight in those areas. Hot spots out west, such as Phoenix, see more than 100 peaks into October in most years.