textproduct: Denver/Boulder

KEY MESSAGES

- Elevated to critical fire weather conditions likely across the high mountain valleys through the next few days.

- Cooler today and Wednesday before temperatures gradually warm back to the triple digits by next weekend.

DISCUSSION /Through Tuesday/

Issued at 157 PM MDT Tue Aug 4 2026

Temperatures are much cooler this afternoon behind yesterday's cold front (around 30 degrees cooler than they were at this time yesterday for the urban corridor and plains). Scattered showers are expected in the South Park and Palmer Divide areas this afternoon. Instability will be enough for an isolated thunderstorm or two as well, but severe weather is not expected. The lower levels are still pretty dry, so our main concern this afternoon will be virga and gusty winds. Overnight, there is a low chance for a few showers and storms in our far northeastern plains, as some sort of weak surface trough sets up and there's some low to mid level convergence. We'll see decent cooling overnight, with below-normal lows in the upper 40s to mid 50s across the plains in the morning.

Tomorrow, the warming trend begins again. The center of the upper level high will push north and slightly east each day as we go into Friday. Highs on Wednesday will warm around 5 to 10 degrees compared to Tuesday. On Thursday, models have a boundary draped across the eastern part of our county warning area from north to south. Winds on the western side will be from the northwest and winds on the eastern side will be from the southeast. There will also be a significant moisture difference between the different sides of the boundary, with much lower dewpoint to its west. The weak downsloping and drier air will allow temperatures on the west side of the boundary to increase into the mid 90s to around 100 degrees. Whereas the east side of the boundary, could be more in the upper 80s to low 90s range. As for the smoke, the near surface smoke from behind the cold front will continue to slowly clear out of the area over the next day or two. Aloft, the NW turning of the winds from the upper ridge building in, will give a brief reprieve from the smoke moving in from Utah. However, with continued NW winds, smoke from the Pacific NW will likely be moved into the area aloft. So, we may not see a complete clearing of the smoke for a while.

Temperatures for the weekend will continue to warm, as the ridge sits over the area. For Saturday and Sunday, portions of the plains around the I-25 and I-70 corridors have a medium to high (50-80%) chance of reaching the triple digits each afternoon (with lower chances in our southern counties). On Sunday, a weak upper level disturbance could move through the flow aloft, bringing the return of low end rain chances for the higher terrain.

AVIATION /18Z TAFS through 18Z Wednesday/

Issued at 1125 AM MDT Tue Aug 4 2026

VFR conditions are expected to prevail through the TAF period, though varying amounts of smoke could lead to occasional slant- range visibility issues through at least Wednesday morning.

Satellite shows nearly all of the morning stratus has burned off, with just a FEW035 left near BJC/EIK/LMO, while thicker stratus still exists over far northeastern Colorado. Winds are currently light and variable, but should become steadier out of the northeast this afternoon with speeds generally under 10kt. A weak cyclone is likely to develop overnight, with light and variable winds returning for most of the terminals. While there is continued uncertainty with winds for Wednesday, most guidance favors a transition to east/northeast winds close to 18z.

FIRE WEATHER

Issued at 157 PM MDT Tue Aug 4 2026

A Red Flag Warning is in effect for North Park and Middle Park this afternoon. Relative humidities are around 11% to 20% as of early this afternoon with wind gusts around 20 to 35mph. Humidities will start to increase and winds will start to decrease around 5PM, rising above critical thresholds around 7PM. Winds are expected to remain breezy tomorrow, with gusts around 20 to 35 mph in the higher terrain. Tomorrow the dewpoints are expected to decrease further, with the drier air expanding further east into the higher elevations. Because of the continued strong winds and expansion of the the low RHs, a Red Flag Warning was issued for the mountain valleys and for elevations above 9000ft for tomorrow.

The drier air and lower dewpoints will continue to expand east into the plains for Thursday and Friday. These lower dewpoints, combined with a warming trend into the weekend, will bring widespread 7% to 15% RHs for Thursday and Friday afternoons. Winds will weaken slightly for Thursday in the higher terrain, but we could still see elevated to critical conditions. In the plains, winds look to generally remain below critical thresholds for Thursday and Friday, but we could have some patchy near- critical to critical conditions in the afternoons.

BOU WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 7 PM MDT this evening for COZ211-213.

Red Flag Warning from noon to 7 PM MDT Wednesday for COZ211>214- 217-218.