Yellowstone National Park, Wyoming

Regional Weather Alerts


     

Alert: Flood Watch
Area(s): Custer
Effective: 2026-09-18 @ 12:03 pm -> 2026-09-19 @ 12:15 pm
Onset: 2026-09-18 @ 7:00 pm -> 2026-09-20 @ 7:00 pm
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Billings MT on 2026-09-18 @ 12:03 pm
Headline: Flood Watch issued September 18 at 11:03AM MDT until September 20 at 6:00PM MDT by NWS Billings MT
Description: A strong and slow moving weather system will impact the region
tonight through Sunday. Well above normal atmospheric moisture levels
combined with the dynamics from this storm system will provide the
potential for heavy rainfall during this period. Thunderstorms
embedded in the more general rainfall will have the potential to
produce flash flooding, particularly over recent burn scars.

* WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...Custer county.

* WHEN...From 6 PM MDT this evening through Sunday afternoon.

* IMPACTS...Excessive runoff may result in flooding of creeks,
streams, and other low-lying and flood-prone locations. Flooding
may occur in poor drainage and urban areas.

* ADDITIONAL DETAILS...
- 1 to 2.5 inches of rainfall is forecast across the watch area
Friday night through Sunday. Locally heavier accumulations up to
4 inches are possible where thunderstorm activity develops.
- Any recent burn scars from this summer will have elevated Flash
Flood potential.
- http://www.weather.gov/safety/flood

Alert: Flood Watch
Area(s): Musselshell; Treasure; Northern Rosebud; Northern Stillwater; Powder River; Northern Park; Golden Valley; Red Lodge Foothills; Northern Big Horn; Southern Rosebud; Judith Gap; Paradise Valley; Livingston Area; Beartooth Foothills; Absaroka/Beartooth Mountains; Crazy Mountains; Southern Big Horn; Southeastern Carbon; Northern Sweet Grass; Bighorn Canyon; Northern Carbon; Pryor/Northern Bighorn Mountains; Melville Foothills; Northeastern Yellowstone; Southern Wheatland; Southwestern Yellowstone; Northeast Bighorn Mountains; Sheridan Foothills
Effective: 2026-09-18 @ 12:03 pm -> 2026-09-19 @ 12:15 pm
Onset: 2026-09-18 @ 7:00 pm -> 2026-09-20 @ 7:00 pm
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Billings MT on 2026-09-18 @ 12:03 pm
Headline: Flood Watch issued September 18 at 11:03AM MDT until September 20 at 6:00PM MDT by NWS Billings MT
Description: A strong and slow moving weather system will impact the region
tonight through Sunday. Well above normal atmospheric moisture levels
combined with the dynamics from this storm system will provide the
potential for heavy rainfall during this period. Thunderstorms
embedded in the more general rainfall will have the potential to
produce flash flooding, particularly over recent burn scars.

* WHAT...Flooding caused by excessive rainfall is possible, along
with Flash Flooding of recent burn scars.

* WHERE...All of South Central Montana, Portions of Southeast
Montana, and Sheridan County Wyoming.

* WHEN...From 6 PM MDT this evening through Sunday afternoon.

* IMPACTS...Excessive runoff may result in flooding of creeks and
other low-lying and flood-prone locations. Flooding may occur in
poor drainage and urban areas.

* ADDITIONAL DETAILS...
- 1 to 2.5 inches of rainfall is expected across the watch area
tonight through Sunday. Locally heavier totals up to 4 inches are
possible where thunderstorm activity is more persistent.
- The Robertson Draw, East Side, Elk, and McGhee-Remington burn
scars are particularly vulnerable to Flash Flooding and debris
flows during the watch period. Any other burn scars from this
summer will have elevated Flash Flood potential as well.
- http://www.weather.gov/safety/flood

Alert: Flash Flood Watch
Area(s): Northwest Beaverhead County
Effective: 2026-09-18 @ 11:39 am -> 2026-09-19 @ 7:00 am
Onset: 2026-09-18 @ 4:00 pm -> 2026-09-19 @ 7:00 pm
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Great Falls MT on 2026-09-18 @ 11:39 am
Headline: Flash Flood Watch issued September 18 at 10:39AM MDT until September 19 at 6:00PM MDT by NWS Great Falls MT
Description: * WHAT...Flash flooding and debris flows caused by excessive rainfall
continue to be possible over the Sand Creek and Bobcat Lakes Burn
Scars.

* WHERE...A portion of southwest Montana, including the following
area, Northwest Beaverhead County.

* WHEN...From 3 PM MDT this afternoon through Saturday afternoon.

* IMPACTS...Heavy rainfall over the Sand Creek and Bobcat Lakes Burn
Scars is expected up to and during the period of the watch.
Residents near the Sand Creek and Bobcat Lakes Burn Scars should
prepare for potential debris flow. Be sure to stay up to date with
information from local authorities. Heavy rainfall could trigger
flash flooding of low-lying areas, urbanized street flooding, and
debris flows in and near recent wildfire burn scars.

* ADDITIONAL DETAILS...
- Showers and thunderstorms capable of producing locally intense
rainfall are forecast to develop over the burn scar late this
afternoon through this evening with additional precipitation
expected through Saturday, which may lead to flash flooding and
debris flows.
- Some locations that may experience flash flooding include...
Areas near the Sand Creek and Bobcat Lakes Burn Scars, including
portions of the Pioneer Mountains Scenic Byway.
- http://www.weather.gov/safety/flood

Alert: Flood Watch
Area(s): Gallatin Valley
Effective: 2026-09-18 @ 11:39 am -> 2026-09-19 @ 7:00 am
Onset: 2026-09-18 @ 7:00 pm -> 2026-09-19 @ 7:00 pm
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Great Falls MT on 2026-09-18 @ 11:39 am
Headline: Flood Watch issued September 18 at 10:39AM MDT until September 19 at 6:00PM MDT by NWS Great Falls MT
Description: The Flash Flood Watch has been changed to a Flood Watch.

Alert: Flood Watch
Area(s): Helena Valley; Meagher County Valleys; Canyon Ferry Area
Effective: 2026-09-18 @ 11:39 am -> 2026-09-19 @ 7:00 am
Onset: 2026-09-18 @ 7:00 pm -> 2026-09-19 @ 7:00 pm
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Great Falls MT on 2026-09-18 @ 11:39 am
Headline: Flood Watch issued September 18 at 10:39AM MDT until September 19 at 6:00PM MDT by NWS Great Falls MT
Description: * WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...The Canyon Ferry Area, Helena Valley, and Meagher County
Valleys in Central Montana

* WHEN...From 6 PM MDT this evening through Saturday afternoon.

* IMPACTS...Excessive runoff may result in flooding of low-lying and
flood-prone locations.

* ADDITIONAL DETAILS...
- Showers and thunderstorms capable of producing hourly rainfall
rates of between 0.25 inch to 0.5 inch are possible.
- Some locations impacted include Helena, Townsend, and White
Sulphur Springs
- http://www.weather.gov/safety/flood

Alert: Flash Flood Watch
Area(s): Little Belt and Highwood Mountains; Big Belt, Bridger and Castle Mountains; Elkhorn and Boulder Mountains
Effective: 2026-09-18 @ 11:39 am -> 2026-09-19 @ 7:00 am
Onset: 2026-09-18 @ 7:00 pm -> 2026-09-20 @ 1:00 am
Severity: Severe
Certainty: Possible
Urgency: Future
Issued By: NWS Great Falls MT on 2026-09-18 @ 11:39 am
Headline: Flash Flood Watch issued September 18 at 10:39AM MDT until September 20 at 12:00AM MDT by NWS Great Falls MT
Description: * WHAT...Flash flooding and debris flows caused by excessive rainfall
are possible over the Horse Gulch area and burn scars from the
summer of 2026.

* WHERE...A portion of central Montana, including the following
areas, Big Belt, Bridger and Castle Mountains, Elkhorn and Boulder
Mountains and Little Belt and Highwood Mountains.

* WHEN...From 6 PM MDT this evening through Saturday evening.

* IMPACTS...Heavy rainfall over the Horse Gulch area and burn scars
from the summer of 2026 is expected up to and during the period of
the watch. Residents near the Horse Gulch area and burn scars from
the summer of 2026 should prepare for potential debris flow. Be
sure to stay up to date with information from local authorities.
Heavy rainfall could trigger flash flooding of low-lying areas,
urbanized street flooding, and debris flows in and near recent
wildfire burn scars.

* ADDITIONAL DETAILS...
- National Weather Service Meteorologists are forecasting heavy
rainfall over recent burn scars, which may lead to flash flooding
and debris flows.
- Some locations that may experience flash flooding include...
Areas near recent burn scars from the summer 2026 and the Horse
Gulch area.
- http://www.weather.gov/safety/flood

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