The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to record temperatures as ETs (not extraterrestrials).😜
Main Topic: Heatwave Pemex Peaks With Relief Coming This Week
Dear Diary. Most of the eastern half of the United States is suffering from yet another major carbon pollution enhanced heatwave that I’ve dubbed Pemex for Mexico’s state-run petroleum company. As most of my followers know, I’ve been naming major heatwaves after oil companies for the last few years to peg why these phenomena are getting worse going further into the 21st century. The good news is that Pemex will peak today, and a cold front will whittle away at the system from north to south starting on Tuesday. The bad news is that many have been and will be suffering from extreme heat for much of this week. I suspect that at least few people will succumb to this heat.
The area covered by National Weather Service heat advisories and warnings on this Monday is quite impressive and probably will be the largest such area covered on any given day of this summer so far:
Pemex, using my scale of 1-5, looks like it is a borderline 3/4 today at its peak. In order for it to be pegged as a historic CAT4 it will kill 500-1000 people. Let’s hope that Pemex hasn’t attained that number once post assessments are written. With time, better air conditioning with more widespread use is preventing deaths. A heatwave of the magnitude of Pemex occurring across the U.S. a hundred years ago would have killed thousands.
Locally, Pemex has made history in a few places such as Tampa:
Here is my criteria for naming heatwaves after oil companies:
Despite high 500 millibar heights a cold from should have sunk towards the Gulf Coast by Saturday:
There are signs that Pemex may have a second max next week since what is left of its heat dome will retrograde towards the U.S. West and grow once more in August:
Here are more details from the Washington Post (for diagrams and reader comments that I did not repost, hit the following link.)
https://www.washingtonpost.com/weather/2025/07/28/us-heat-wave-temperature-records
The heat wave in the Eastern U.S. is peaking. When will it finally ease?
About 200 million people are under some sort of heat alert Monday, including 24 million under the highest alert — extreme heat warning — for scorching conditions.
July 28, 2025 at 11:13 a.m. EDT
People try to stay cool in Brooklyn on Friday, when the heat index topped 100 degrees. (Spencer Platt/Getty Images)
Dangerous heat is gripping much of the eastern half of the country to start the week — but it will loosen that hold significantly by the weekend.
About 200 million people are under some sort of heat alert Monday, including 24 million under the highest alert — extreme heat warning — for scorching conditions. The heat stretches from South Dakota to Texas, then eastward, including most locations from the southern Great Lakes south to the East Coast.
The areas with extreme heat warnings include Des Moines, St. Louis, Memphis, New Orleans, Jacksonville, Florida, and Raleigh, North Carolina, among others. These cities will see heat-index values rise near 110 or 115, with temperatures ranging from 95 to the low 100s.
Areas of Level 4 out of 4 heat risk run from much of the Florida Peninsula northward to Georgia and the Carolinas. Level 3 out of 4 risk covers a region from the eastern Plains, through the Midwest and Mid-South, then to the Mid-Atlantic coast. At Level 3 out of 4, heat illness becomes a concern for the general population.
The high heat Monday follows similar conditions that spread across the weekend.
Sunday offered a record high in Tampa, where it reached 100 degrees for the first time since observations began in 1890. Other locations also surpassed that mark, setting daily records, with more to come.
But there is an end in sight. Heat will begin sweeping southeastward with a cold front in the coming days. This weekend, most of the eastern U.S. should see at least a short period of below-average temperatures.
More heat Monday
Numerous records are expected Monday. The heat will largely target the Southeast and Florida, where highs are about 10 degrees above normal for the date.
Afternoon readings near and above 100 degrees are expected from around Orlando through central Georgia and to parts of the Carolinas. This comes off uncomfortably muggy morning lows also near records, running about mid-70s to around 80 in much of the Southeast.
Heat indexes will rise to around 110 degrees in much of the same zone, thanks to moderately high humidity in place.
Temperatures around 100 will also overtake most of the Plains to Mississippi Valley; Dallas, Oklahoma City and Little Rock are all expected to rise close to the century mark. Pooled high humidity in the Mississippi Valley and central Plains to Midwest will make it particularly dangerous for portions of those regions, perhaps pushing localized heat indexes toward 120.
On the heels of weekend records
The heat footprint and intensity on Monday are near the peak for this heat wave, and are quite close to conditions seen Sunday, when Tampa reached a record 100 degrees for the first time in its 135-year weather history.
Although no stranger to summery days, Tampa’s proximity to the Gulf of Mexico and a summer wet season tends to moderate readings compared to locations with plentiful landmass upstream. Before Sunday’s record, the city reached 99 on two occasions, most recently in 2020.
The city of Jacksonville hit 100 on Sunday as well, which tied a record for the date there. In Fort Myers, temps hit 97, also a tie for a daily record.
Saturday featured record heat a bit farther north, with North Carolina a favored location for the hottest conditions. Temperatures hit 101 in Charlotte and Greenville-Spartanburg, both records for the date.
What to expect through Wednesday
There won’t be much change Tuesday near and east of the Mississippi River, as a cold front sags south through the central Plains and Upper Midwest.
As heat pulses upward again in the Mid-Atlantic and Northeast ahead of that cold front, highs in the mid-90s to around 100 may threaten records both Tuesday and Wednesday along the urban corridor from D.C. to Boston.
Additional records, with temperatures well into the 90s to around 100, are likely again in Florida.
The area of highest heat gets squeezed farther east Wednesday and eventually pushed into the Southeast on Thursday.
When will we get some relief from the heat?
Pleasant weather arrives for many sunbaked spots by late this week and into the weekend.
Below-average temperatures are expected to envelop most of the Lower 48 for a time, bringing widespread zones of readings 5 to 10 degrees below what’s typical for early August.
Many places in the northeast quadrant of the contiguous U.S. will see high temperatures about 20 degrees cooler from midweek to the weekend.
On Saturday, highs are forecast to top out around 80 as far south as Atlanta and the Carolinas, with 70s widespread in the Northeast.
Dew points — a measure of moisture in the air — that soared well into the 60s and 70s across the eastern U.S. throughout the heat wave will often be replaced by values in the upper 40s to around 60. Such readings are considerably more comfortable and may get some thinking about the next season to come.
The intense heat is probably more persistent in Florida and the Gulf Coast, and the hottest weather relative to normal begins to shift west as it abates in the east. For now, although the coolness relative to normal won’t be long-lasting, it doesn’t appear an immediate return to extreme readings is in the offing.
By Ian Livingston Ian Livingston is a forecaster/photographer and information lead for the Capital Weather Gang. By day, Ian is a defense and national security researcher at a D.C. think tank.
More:
Here are more “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Here is More Climate News from Monday:
(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)