textproduct: Western and Central Wyoming

KEY MESSAGES

- The heat wave begins this afternoon with highs in the 90s and 100s for the lower elevations, with hottest temperatures in the Big Horn Basin where some highs will approach 105. Heat will continue through at least Tuesday.

- Sunday will be the hottest day with some all time station record highs likely pushing 110 degrees.

- Elevated to near critical fire weather is likely the next four days. Critical fire weather is likely Sunday afternoon and once again on Tuesday afternoon.

UPDATE

Issued at 1200 PM MDT Sat Jul 11 2026

No changes with the forecast. IR shows clear skies over much of the state with dry conditions expected for the weekend. Widespread triple digits expected this afternoon and even a bit hotter for Sunday. Similar temperatures for Monday and Tuesday as Saturday a couple degrees but a few degrees less heading into the rest of the work week as storm chances increase as well.

DISCUSSION

Issued at 219 AM MDT Sat Jul 11 2026

I do not have the traditional path for a meteorologist 4 years of college right out of high school. Let us say if has been a bit of a wavy route for this career. I dropped out of college for a while to work some blue collar jobs. And with the weather coming up the next few days, it remains me of a couple of them. One is roofing, which I did North Carolina during a couple of summers, including using torches. Another was working in a liquid packaging plant, in the extruder department, where we had 4 of them running at 500 degrees to put coating on cartons. As you would expect, these jobs were HOT. And the temperatures the next few days will let me flash back to these jobs I worked almost 30 years ago (yes, I'm old). We have two main hazards, heat and fire weather, and we cover each of these separately.

HEAT...This will be most widespread hazard. We have continued the excessive heat warning as is for now. I could see extending it another day through Tuesday, but we will hold off for now. Reasoning remains the same, with a ridge of high pressure over the desert southwest building northward through the weekend, ending up centered over the northern Rockies for the weekend, with 500 millibar heights as high as 6000 meters on some runs of the ensembles. The 700 millibar temperatures climb as high as 21 celsius today, and this translates to just about all locations being above 90 degrees for high temperatures today. Locations below 5200 feet have at least a 1 in 2 chance of high temperatures over 100 today, with an almost 100 percent chance in the warmest spot, the stretch from Thermopolis to Lovell. The stretch from Worland to Greybull has a 1 in 2 chance of high temperatures over 105.

The peak of the heat will likely be Sunday. The 700 millibar temperatures climb about 2 to 3 degrees celsius, bringing temperatures about 3 to 5 degrees warmer. There will also be a bit more wind in northern Wyoming, bringing better mixing. The chance of high temperatures over 100 is around 4 out of 5 below 6000 feet on this day, and includes locations where this is rare including Green River and Cody. Even downtown Jackson has around a 1 in 2 chance. The most impressive is the area of greater than 4 out of 5 chance of 105 degrees or greater, which stretches from Thermopolis almost to the Montana border through the Big Horn Basin, as well as much of eastern Johnson County. And we continue to have at least a 1 in 2 chance of high temperatures over 110 degrees from Worland to Greybull. If that occurred, these would be all time station record high temperatures. These are possible at a lot of lower elevation locations though.

With slightly lower temperatures aloft and somewhat less wind, Monday will be a few degrees cooler. However, the chance of high temperatures over 100 will still be 4 out of 5 or greater below 5500 feet on this day. And now, even Tuesday looks just as hot, with similar conditions as the ridge holds. We may need to extend the excessive heat warning another day but we will hold off for now. The extreme heat looks to end Wednesday as the ridge weakens somewhat, but above normal temperatures should continue into next weekend.

FIRE WEATHER...Elevated fire weather remains likely today with the hot temperatures and humidity falling into the single digits across much of the area. However, with wind expected to remain light to moderate, critical fire weather is not expected this afternoon. This will likely change Sunday as wind increases, with gusts to 30 mph possible across Wyoming. With the record heat and very low humidity (as low as 5 percent). The northern zones look most likely to reach Red Flag criteria here, further south, especially in Fremont County, it is a bit more questionable. For now, in coordination with our neighbors to the north, we will maintain the watch and let the day shift make the finally call. On Monday, wind should decrease enough for conditions to not be critical. There could be another period of critical fire weather on Tuesday afternoon. However, increasing moisture and somewhat higher humidity will be a factor. Plenty of time to decide on this though.

Otherwise, things look dry through the weekend. Strong ridging and warm air aloft should cap the atmosphere and prevent convection and even much in the way of cloud cover. I can't completely rule out a virga shower over the mountains late this afternoon, but the chance is less than 1 out of 10 so we left the forecast dry. Starting on Monday, some mid level moisture may wrap around the backside of the ridge and could bring an isolated thunderstorm to the western mountains. With the chance less than 1 out of 10 though, we have left the forecast dry for now. By Tuesday and especially on Wednesday, moisture should be deep enough for a chance of diurnal convection each day through Friday. It is difficult to pinpoint a more active day at this time though. So, to sum it up, prepare for a stretch of heat over the next four days we have not seen in a while.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1101 AM MDT Sat Jul 11 2026

VFR conditions through the period. A mostly clear sky today, with nearly no precipitation chances. The exception may be around KLND as a few weak showers develop off the southern end of the Wind River Mountains. Surface temperatures will be hot today, 90 to 100 degrees. Near the end of the period, south to southeast winds begin to increase.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts.

FIRE WEATHER

Issued at 1200 PM MDT Sat Jul 11 2026

Elevated to near critical fire weather conditions this afternoon and evening due to very hot temperatures and minimum relative humidity values dropping to below 10 percent. Winds will remain relatively light. Gusty southeast winds up to 25 to 35 mph will combine with record high temperatures and minimum relative humidity as low as 5 percent to bring near critical to critical fire weather to much of northern and central Wyoming. Poor relative humidity recovery overnight dropping once again for Monday afternoon. Wind, however, will become relatively light once again with similar fire weather conditions as Saturday afternoon and evening.

RIW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 9 PM MDT Monday for WYZ003>006-010- 011-013-016>020-023-025>030.

Red Flag Warning from 11 AM to 10 PM MDT Sunday for WYZ275-276- 280>283.