textproduct: Western and Central Wyoming

KEY MESSAGES

- One more very hot day with highs over 100 degrees for many of the lower elevations. More record high temperatures are possible this afternoon.

- Low humidity and a gusty breeze will bring elevated to critical fire weather for much of the area this afternoon, continuing in southern Wyoming into Monday.

- A cold front will bring cooler temperatures Monday and Tuesday, especially in northern and central Wyoming which will likely be 20 to 25 degrees cooler than today. Above normal temperatures will likely return later in the week.

DISCUSSION

Issued at 1236 AM MDT Sun Aug 2 2026

It certainly has been a hot stretch in Wyoming through July and starting August. For example, at the humble Riverton Weather Abode, of the past 29 days, 28 have averaged above normal. And the one day that was below average, July 23rd, was only 0.2 degrees below normal. We have had 7 high temperatures over 100, we typically average less than 1 a year. And we will almost certainly have another one today. However, there is something moving toward the area that will bring a welcome break from one of the hottest summers we have had in quite a while. More on that later in the discussion.

But we have one more scorching hot day to get through. We had several record highs that were broken or tied yesterday, including an all time August record high temperature at the Riverton airport. It was also the first time it has been 100 at the airport in the month of August (since 1996 when the ASOS was commissioned). The 700 millibar temperatures look largely unchanged from yesterday, so the high temperatures forecasted for Sunday also look relatively unchanged. With a southwesterly breeze developing, the areas that will be warmer will be the downslope locations. These include the southern Bighorn Basin, the Wind River Basin and Lander Foothills and portions of Sweetwater County. We will likely see more daily record high temperatures today. Some all time August high temperatures records could also be in jeopardy. It still looks like elevations below around 5800 feet have at least a 1 in 2 chance of high temperatures over 100F. As for highs of 105F, the 1 in 2 chance is largely below 4500 feet, mainly in portions of Fremont County as well the Big Horn Basin from Thermopolis to Worland. And the gusty breeze will also bring increased fire weather concerns. This, combined with relative humidity falling as low as 5 percent, will bring at least elevated fire weather to the entire area. A Red Flag Warning is in effect for much of the area, and we will continue it. I did give some thought to including Natrona County, but still have some doubts if the wind will be of sufficient strength or duration. Nevertheless, burning is strongly discouraged anywhere in western and central Wyoming today.

The relief from the heat for some will come in the form of a cold front dropping southward out of Montana tonight and tomorrow. It will begin to weaken as it moves through the area Monday, but all areas will see a drop in temperatures. The most pronounced drops will be across northern Wyoming where places Cody could see temperatures 25 degrees cooler than today with it feeling more like September. Most locations East of the Divide will see around a 15 to 20 degree drop in temperatures, with some locations seeing the coolest temperatures since June. It will also cool off West of the Divide, but not as much. However, 8 to 15 degrees will still feel better. We still have fire weather concerns on this day though. In northern and central Wyoming, the cooler temperatures and somewhat higher humidity should keep conditions below critical despite a gusty northerly breeze. Much of southern Wyoming will still have humidity under 15 percent though. And with the continued wind with the front in the area, critical fire weather still looks likely so the Red Flag Warning will be continued.

Tuesday looks like the coolest day across much of the area. There will still be a bit of a breeze and humidity remains low so we may need more fire weather highlights for this day as well although it is more borderline. We will have more time to look at that in future shifts. Following that, the ridge should again build across the desert southwest and then build back northward into Wyoming. This means temperatures rising again by Wednesday with above normal temperatures again likely from Thursday into next weekend, with 90s once again likely in many of the lower elevations. As for any precipitation chances, there are rather slim pickings. A weak shortwave will move across northern Wyoming and may bring a few showers and storms Tuesday afternoon or evening but with little moisture available coverage looks rather sparse. Mainly dry weather then continues for the rest of the week. There are some indications in some of the long range guidance of the ridge weakening early next week and maybe some monsoonal moisture returning for early next week but a lot of uncertainty this far out. So, enjoy the brief break from the hot weather early this week because it will likely not last long.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 415 AM MDT Sun Aug 2 2026

VFR conditions through the next 24 hours with only high cirrus sweeping through. Main forecast issue is gusty winds on Sunday. Many areas will be gusting 15 to 25 knots through the afternoon, which will likely hold on a few hours into the late evening Sunday night. Wind will be lightest in vicinity of KCPR. Smoke may be a little more noticeable all sites tomorrow due to significantly increased fire activity across the western US. KJAC may be most impacted, due to the Big Rock Fire just to the west in eastern Idaho. Wind will switch to the north after 06Z at Cody and around 12Z Monday at Worland as a cold front drops southward out of Montana.

FIRE WEATHER

Issued at 1236 AM MDT Sun Aug 2 2026

A combination of very hot temperatures, humidity falling into the single digits and a gusty southwesterly breeze will bring elevated to critical fire weather to most of the area today. A cold front drops southward on Monday. Fire concerns should lessen across northern and central Wyoming as cooler temperatures and higher humidity moves in behind the front. However, in southern Wyoming, critical fire weather should continue with a gusty wind and relative humidity remaining below 15 percent.

RIW WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 10 PM MDT this evening for WYZ003>006-010- 011-013-016>020-023-025>030.

Red Flag Warning from 1 PM this afternoon to 9 PM MDT this evening for WYZ275-276-282-283-285.

Red Flag Warning from 1 PM this afternoon to 9 PM MDT Monday for WYZ277>279-289.