Alert archive / Colorado / Red Flag Warnings in 2025
Red Flag Warning 21, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this red flag warning at Aug 4, 2025, 2:09 PM MDT for 8 counties in Colorado. It took effect at Aug 5, 2025, 11:00 AM MDT. It was in force for 9 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 4, 2025, 2:09 PM MDT (20:09 UTC)
- In effect from
- Aug 5, 2025, 11:00 AM MDT
- Expired
- Aug 5, 2025, 8:00 PM MDT
- In force
- 9 hr
- Issued by
- NWS Denver/Boulder, CO
Counties Boulder County, CO, Clear Creek County, CO, Gilpin County, CO, Grand County, CO, Jackson County, CO, Larimer County, CO, Park County, CO, Summit County, CO
The radar
The Denver radar (KFTG), 108 km from the middle of the area, began a volume at 20:08 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Riverton, WY (KRIW), launched 12:00Z, 8.2 hours before the alert went out and 407 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 118 J/kg
- Mixed-layer CIN
- -288 J/kg
- Mixed-layer LCL
- 2052 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- -7 m²/s²
- 0-3 km storm-relative helicity
- 60 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
838 WWUS85 KBOU 042009 RFWBOU URGENT - FIRE WEATHER MESSAGE National Weather Service Denver/Boulder CO 209 PM MDT Mon Aug 4 2025 COZ211>214-217-218-051200- /O.NEW.KBOU.FW.W.0021.250805T1700Z-250806T0200Z/ Jackson County Below 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Grand and Summit Counties Below 9000 Feet- Central and Southeast Park County- West Jackson and West Grand Counties Above 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- 209 PM MDT Mon Aug 4 2025 ...RED FLAG WARNING IN EFFECT FROM 11 AM TO 8 PM MDT TUESDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN MOUNTAINS AND HIGH MOUNTAIN VALLEYS...FIRE WEATHER ZONES 211 THROUGH 214...217...AND 218... The National Weather Service in Denver has issued a Red Flag Warning for wind and low relative humidity, which is in effect from 11 AM to 8 PM MDT Tuesday. * AFFECTED AREA...Fire Weather Zones 211, 212, 213, 214, 217 and 218. * TIMING...From 11 AM to 8 PM MDT Tuesday. * WINDS...West 15 to 20 mph with gusts up to 30-35 mph. * RELATIVE HUMIDITY...As low as 8 percent. * IMPACTS...Conditions will be favorable for rapid wildfire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
3 follow-up statements
870 WWUS85 KBOU 050929 RFWBOU URGENT - FIRE WEATHER MESSAGE National Weather Service Denver/Boulder CO 329 AM MDT Tue Aug 5 2025 COZ211>214-217-218-052130- /O.CON.KBOU.FW.W.0021.250805T1700Z-250806T0200Z/ Jackson County Below 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Grand and Summit Counties Below 9000 Feet- Central and Southeast Park County- West Jackson and West Grand Counties Above 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- 329 AM MDT Tue Aug 5 2025 ...RED FLAG WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO 8 PM MDT THIS EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN MOUNTAINS AND HIGH MOUNTAIN VALLEYS...FIRE WEATHER ZONES 211 THROUGH 214...217...AND 218... * AFFECTED AREA...Fire Weather Zones 211, 212, 213, 214, 217 and 218. * TIMING...From 11 AM this morning to 8 PM MDT this evening. * WINDS...West 10 to 20 mph with gusts up to 35 mph. * RELATIVE HUMIDITY...As low as 8 percent. * IMPACTS...Conditions will be favorable for rapid fire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
623 WWUS85 KBOU 052004 RFWBOU URGENT - FIRE WEATHER MESSAGE National Weather Service Denver/Boulder CO 204 PM MDT Tue Aug 5 2025 ...PROLONGED PERIOD OF CRITICAL FIRE WEATHER CONDITIONS THROUGH FRIDAY... .A hot and dry airmass will hold across the area through Friday. It will be breezy at times, especially during the afternoon and early evening hours, leading to potential for rapid wildfire spread. While Red Flag Warnings are in effect through Wednesday, critical fire weather conditions will likely exist Thursday and again on Friday. Slight relief should come through the weekend with a gradual cooling trend and winds diminishing by Sunday. COZ211-213-217-218-061200- /O.NEW.KBOU.FW.W.0022.250806T1800Z-250807T0200Z/ /O.CON.KBOU.FW.W.0021.000000T0000Z-250806T0200Z/ Jackson County Below 9000 Feet- Grand and Summit Counties Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- 204 PM MDT Tue Aug 5 2025 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN MOUNTAINS AND HIGH VALLEYS...FIRE WEATHER ZONES 211, 213, 217, AND 218... ...RED FLAG WARNING IN EFFECT FROM NOON TO 8 PM MDT WEDNESDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN MOUNTAINS AND HIGH VALLEYS...FIRE WEATHER ZONES 211, 213, 217, AND 218... The National Weather Service in Denver has issued a Red Flag Warning for wind and low relative humidity, which is in effect from noon to 8 PM MDT Wednesday. * AFFECTED AREA...Fire Weather Zones 211, 213, 217 and 218. * TIMING...For the first Red Flag Warning, until 8 PM MDT this evening. For the second Red Flag Warning, from noon to 8 PM MDT Wednesday. * WINDS...West 15 to 20 mph with gusts to around 30 mph. * RELATIVE HUMIDITY...As low as 6 percent today, and as low as 10 percent Wednesday. * IMPACTS...Conditions will be favorable for rapid wildfire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$ COZ212-214-060200- /O.CON.KBOU.FW.W.0021.000000T0000Z-250806T0200Z/ South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Central and Southeast Park County- 204 PM MDT Tue Aug 5 2025 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM MDT THIS EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR THE MOUNTAINS AND HIGH MOUNTAIN VALLEYS AROUND PARK AND SUMMIT COUNTIES...FIRE WEATHER ZONES 212 AND 214... * AFFECTED AREA...Fire Weather Zones 212 and 214. * TIMING...Until 8 PM MDT this evening. * WINDS...West 15 to 20 mph with gusts up to 30 mph. * RELATIVE HUMIDITY...As low as 6 percent. * IMPACTS...Conditions will be favorable for rapid wildfire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
728 WWUS85 KBOU 060156 RFWBOU URGENT - FIRE WEATHER MESSAGE National Weather Service Denver/Boulder CO 756 PM MDT Tue Aug 5 2025 ...PROLONGED PERIOD OF CRITICAL FIRE WEATHER CONDITIONS THROUGH FRIDAY... .A hot and dry airmass will hold across the area through Friday. It will be breezy at times, especially during the afternoon and early evening hours, leading to potential for rapid wildfire spread. While Red Flag Warnings are in effect through Wednesday, critical fire weather conditions will likely exist Thursday and again on Friday. Slight relief should come through the weekend with a gradual cooling trend and winds diminishing by Sunday. COZ211-213-217-218-061200- /O.EXP.KBOU.FW.W.0021.000000T0000Z-250806T0200Z/ /O.CON.KBOU.FW.W.0022.250806T1800Z-250807T0200Z/ Jackson County Below 9000 Feet- Grand and Summit Counties Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- 756 PM MDT Tue Aug 5 2025 ...RED FLAG WARNING REMAINS IN EFFECT FROM NOON TO 8 PM MDT WEDNESDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN MOUNTAINS AND HIGH VALLEYS...FIRE WEATHER ZONES 211, 213,217, AND 218... * AFFECTED AREA...Fire Weather Zones 211, 213, 217 and 218. * TIMING...From noon to 8 PM MDT Wednesday. * WINDS...Southwest 10 to 20 mph with gusts up to 30 mph. * RELATIVE HUMIDITY...As low as 7 percent. * IMPACTS...Conditions will be favorable for rapid fire spread. Avoid outdoor burning and any activity that may produce a spark and start a wildfire. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$ COZ212-214-060300- /O.EXP.KBOU.FW.W.0021.000000T0000Z-250806T0200Z/ South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Central and Southeast Park County- 756 PM MDT Tue Aug 5 2025 ...RED FLAG WARNING WILL EXPIRE AT 8 PM MDT THIS EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR THE MOUNTAINS AROUND SUMMIT AND PARK COUNTIES AND SOUTH PARK... Humidities will be a little higher and winds a little lighter on Wednesday. It will still be very warm and dry with near critical conditions. $$ Gimmestad
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 4, 2:47 PM MDT | Special Weather Statement | BOU | Morgan | 43 min |
| Aug 4, 3:31 PM MDT | Special Weather Statement | BOU | Washington | 44 min |
| Aug 4, 4:12 PM MDT | Special Weather Statement | BOU | Washington | 48 min |
| Aug 4, 4:27 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 33 min |
| Aug 4, 4:45 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 30 min |
| Aug 4, 4:57 PM MDT | Special Weather Statement | BOU | Washington | 33 min |
| Aug 4, 5:07 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 38 min |
| Aug 4, 5:14 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln, Washington | 46 min |
| Aug 4, 5:54 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln, Washington | 36 min |
Nearby
Red Flag Warnings in Colorado, 2025Every red flag warning in 2025
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.