Yellowstone National Park, Wyoming
Regional Weather Alerts
| Alert: | Flood Advisory |
| Area(s): | Golden Valley, MT; Sweet Grass, MT |
| Effective: | 2026-09-18 @ 8:08 pm -> 2026-09-18 @ 11:15 pm |
| Onset: | 2026-09-18 @ 8:08 pm -> 2026-09-18 @ 11:15 pm |
| Severity: | Minor |
| Certainty: | Likely |
| Urgency: | Expected |
| Issued By: | NWS Billings MT on 2026-09-18 @ 8:08 pm |
| Headline: | Flood Advisory issued September 18 at 7:08PM MDT until September 18 at 10:15PM MDT by NWS Billings MT |
| Description: |
* WHAT...Flooding caused by excessive rainfall is expected. * WHERE...Southwestern Golden Valley County in central Montana... Northeastern Sweet Grass County in south central Montana... * WHEN...Until 1015 PM MDT. * IMPACTS...Minor flooding in low-lying and poor drainage areas. Rises in small streams and normally dry arroyos. * ADDITIONAL DETAILS... - At 708 PM MDT, Doppler radar indicated heavy rain due to thunderstorms. Minor flooding is ongoing or expected to begin shortly in the advisory area. Between 0.5 and 1.5 inches of rain have fallen. - Some locations that will experience flooding include... Mainly rural areas of Southwestern Golden Valley and Northeastern Sweet Grass Counties. - http://www.weather.gov/safety/flood |
| Alert: | Flash Flood Warning |
| Area(s): | Golden Valley, MT; Wheatland, MT |
| Effective: | 2026-09-18 @ 7:52 pm -> 2026-09-18 @ 10:00 pm |
| Onset: | 2026-09-18 @ 7:52 pm -> 2026-09-18 @ 10:00 pm |
| Severity: | Severe |
| Certainty: | Likely |
| Urgency: | Immediate |
| Issued By: | NWS Billings MT on 2026-09-18 @ 7:52 pm |
| Headline: | Flash Flood Warning issued September 18 at 6:52PM MDT until September 18 at 9:00PM MDT by NWS Billings MT |
| Description: |
At 652 PM MDT, Doppler radar indicated thunderstorms producing heavy rain across the warned area. Between 1.5 and 2.5 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. Some locations that will experience flash flooding include... Mainly rural areas of Southwestern Golden Valley and Southeastern Wheatland Counties. |
| 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 |
