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 extreme or record temperatures as ETs (not extraterrestrials).😉
Main Topic: First Major Heatwave Will Strike Texas This Week
Dear Diary. Right on cue (because climate change produces heatwaves earlier during the spring) a monster heatwave will affect Texas with its talons stretching into the northern Plains and much of the South.
Around here we judge such systems on a scale of one to five, much like that of the Saffir-Simpson scale for hurricanes. Looking at the current state of NWS advisories over Texas, we have a one since we do see advisories, but there are no heat warnings in effect:
Fire weather advisories are also up for the Southwest and the northern Plains where record heat is expected today.
My criteria for naming heatwaves can be read here:
If the current heatwave ratchets up to a major three, and by most indications it will later this week, the first name out the box will be Marathon.
https://en.wikipedia.org/wiki/Marathon_Oil
Looking at the May weather pattern Marathon should be a fitting name because I don’t see it ending anytime soon, unfortunately.
Here are more details from the Washington Post:
https://www.washingtonpost.com/weather/2025/05/13/heat-wave-us-texas-record-temperatures
Much of Texas is staring down temperatures in the upper 90s to 105 for the week
Heat is soaring in Texas, and from Mexico to Canada, lots of daily heat records will be threatened.
May 13, 2025
The first major heat wave of the year is sweeping across a large swath of North America, delivering extreme conditions from Mexico to Canada with the United States — and Texas in particular — at the heart of the high temperatures.
In coming days, the hottest weather will focus there and in portions of the South. In Texas, a large area of the state is expected to experience temperatures of up to 15 to 25 degrees above normal — into the 90s and 100s in all but a few locations.
It will be enough to push heat risk to major (Level 3 out of 4) or extreme (Level 4 out of 4) risk in much of southern Texas, including San Antonio, Houston, Austin and Laredo. That will be the case at least into the weekend if not beyond.
A heat advisory has already been issued for much of the state’s south — and it’s a good bet that there will be more.
“Many will not be acclimated to this type of heat so early within the year and thus the risk for heat-related illness is higher than normal,” the National Weather Service office in Austin warned. “Temperatures have a high chance of setting new daily record highs and are expected to near, if not exceed, all-time record highs for the month of May.”
This follows intense conditions that developed underneath an early season heat dome over the weekend in the western U.S. before shifting east. It’s preparing to settle into the South for a longer stay.
Heat core shifting south
Early this week, the hottest readings relative to the usual are shifting from the north to the south. In Texas, cities including Dallas, Austin, Houston and Corpus Christi are staring down temperatures in the upper 90s to 105 degrees or higher. In the state’s central and south, the records will keep coming for days.
Houston is forecast to reach the mid-90s on Tuesday, the upper 90s both Wednesday and Thursday and mid-90s again on Friday.
Along the Rio Grande, temperatures are expected to rise near and above 110 degrees each day over the next week. On Wednesday, a forecast of 115 degrees would set a new U.S. high mark for the year.
Heat index values will be even more dramatic in Southeast Texas, adding about 5 degrees to actual readings. Widespread heat indexes of 110-plus are expected in south and southeast portions of the state on Wednesday, and humidity will build further into the weekend.
By the end of the week, temperatures will still be hot in much of Texas as near 90 to mid-90s highs also spread east along the northern Gulf Coast region as well as into Florida and parts of the Southeast.
Records at risk
These readings should threaten dozens of daily records through the rest of the week.
On Tuesday, records are a risk largely in Texas but remain so across a chunk of the northern tier. The potential for record heat will stretch into the Southeast over time.
A number of locations could see not only records for the day but also for the month, and the earliest in the season that it has gotten so hot.
- Forecasts for Tuesday through Friday in Houston would set a daily record on each afternoon. If it hits 100 degrees, it will be the earliest high temperature there by more than two weeks. The record holder is June 2, 2011.
- Austin could reach 100 degrees as soon as Tuesday, then 100-plus each day through at least Saturday and perhaps beyond. If it hits 102 as forecast Wednesday it will tie for the hottest reading this early in the year. The most 100-degree highs in Austin in May is three during 2011.
- Del Rio, on the border with Mexico, should come close to its hottest May temperature on record of 112 degrees, set just last year. Before 2024, the May record was 109 degrees.
Heat wave so far
This heat wave has delivered at least dozens of daily records across North America since the weekend. It brought the hottest weather of this young season to a region from California through the Rockies and then into the north-central U.S.
Some headlines through Monday include:
- Canada saw its earliest day at or above the century mark on record. It hit 100 degrees on the nose (37.8 Celsius) on Sunday in Emerson near the international border south of Winnipeg.
- International Falls, Minnesota, reached 96 degrees, the hottest so early by almost a month and hottest in any May. This is hotter than it gets in many years, including during 2024.
- Daily records near or above 100 degrees were set in much of the interior Southwest over the weekend, including around Los Angeles, where it reached 99 degrees.
- The highest temperature of the year in the U.S. so far was in Death Valley on Saturday when it hit 112 degrees. In Mexico, it reached 113 degrees at Hermosillo in the Sonora state to the south of Arizona, the hottest reliable reading of the year in that nation.
A similar set of stories will probably unfold over coming days.
Summer preview
Hotter and more frequent heat waves are a symptom of human-caused climate change. Many of the same spots have been plagued by repeated rounds of intense heat in recent years.
And looking ahead, the Climate Prediction Center is calling for above-average temperatures in most of the country during climatological summer (June through August), with the intermountain west and Great Basin having the highest odds area for warm readings. New weather modeling suggests the same.
By Ian LivingstonIan 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 “ETs” 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 Tuesday:
(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.)