NWS Riverton WYFW.W 0027September 8, 2026
Red Flag Warning: Natrona County/Casper BLM, Granite/Green/Ferris/Rattlesnake Mountains and Casper Mountain, WY
The National Weather Service office in Riverton issued a red flag warning for Natrona County/Casper BLM, Granite/Green/Ferris/Rattlesnake Mountains and Casper Mountain in Wyoming, which was in force until 9:00 p.m. local time on September 10. It was the 27th red flag warning the NWS office in Riverton issued in 2026. Wyoming had 16 red flag warnings in September 2026, against 16 in an average September of 2008-2025 (Wyoming's red flag warnings by year).
ExpiredWarning
In force for 2 days; it has expired. The agency may have replaced it with a new notice.
The notice
- Issued by
- National Weather Service, Riverton WY
- Area
- Natrona County/Casper BLM, Granite/Green/Ferris/Rattlesnake Mountains and Casper Mountain
- State
- Wyoming
- Level
- Warning
- Issued
- 12:58 a.m. MDT, September 8, 2026
- In force from
- 12:00 p.m. MDT, September 8, 2026
- Expires
- 9:00 p.m. MDT, September 10, 2026
- CAP severity, certainty, urgency
- Severe, Likely, Expected
- VTEC event
- KRIW FW.W 0027
- Official source
- National Weather Service: the notice at its source
Red Flag Warnings in Wyoming since 2008Every warning type in Wyoming
Source: National Weather Service: the notice at its source. AreaZine rebuilds this page from the agency's record; the agency's page is the one to act on. A U.S. Government work, in the public domain.
The notice as issued
The National Weather Service in Riverton has issued a Red Flag Warning, which is in effect from noon today to 9 PM MDT Thursday. * IMPACTS: Low Humidities...Strong Gusty Winds...and Wind Shift with a Cold Front could cause erratic fire behavior. * AFFECTED AREA: In Central WY...Fire Weather Zones 280...289 and 300. * COUNTIES AFFECTED: In Central WY...Fremont...Natrona. In Southwest WY...Sweetwater. * COLD FRONT: Winds will turn more northerly after sunset tonight, as a cold front comes down from the north. * WIND: Tuesday - West to southwest 15 to 25 mph with gusts up to 35 mph. Wednesday - West to southwest 10 to 15 mph with gusts up to 25 mph. Thursday West to southwest 15 to 25 mph with gusts up to 45 mph. * HUMIDITY: Tuesday - Ranging between 11 to 18 percent. Wednesday - As low as 8 percent. Thursday - As low as 7 percent.
What the agency told people to do
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.
Source: National Weather Service: the notice at its source. The text is the agency's, unedited. A U.S. Government work, in the public domain.