September rainfall amounts were among the driest on record. This allowed drought conditions in northeast Montana to persist.
Every event with a place to put it; 16 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GGW wrote it up.
September rainfall amounts were among the driest on record. This allowed drought conditions in northeast Montana to persist.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Glasgow, MT wrote its last area forecast discussion before the first event at Aug 31, 1:12 PM MST, 10 hours 48 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 212 PM MDT Tue Aug 31 2021 .DISCUSSION... A few features are coming together for the possibility of strong storms to affect the northern zones tonight. However chances look really small as much of the activity should remain to our north. An upper low over southern British Columbia is bringing SW flow across the area while near the surface, a surge of moist and unstable air is moving in on SE winds over the eastern zones. Slight deviations in the inhibition could allow these to drop into the northern zones. Upper low swings into the Prairie Provinces Wednesday with a cool airmass to settle in. The upper low will stay far enough north so that we stay dry while another disturbance passes by grazing our southern zones Friday. Weak ridging should give the Labor Day weekend some warmth but Fire Weather concerns may also be elevated. Another trough brings a cooldown early next week. TFJ && .AVIATION... VFR. Last Update: 2000z A cold front will move into eastern Montana tonight with increasing NW winds behind it. Isolated thunderstorms to the north of the airports may also bring gusty/erratic winds from after 03z. Look for quiet conditions Wednesday with a NW breeze. TFJ && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && weather.gov/glasgow
The national radar mosaic for the moment the first event began.
16 drought. Local standard time, as filed.
To start September, ongoing drought conditions in Sheridan County were at (D3-Extreme) in southern and western areas of Sheridan County, while the northeastern half of Sheridan County was in (D2-Severe). By the end of September the whole county worsened to (D3-Extreme) conditions.
To start September, ongoing drought conditions in Daniels County were at (D3-Extreme) in the eastern two thirds of the county, while the western third was in (D4-Exceptional) drought conditions. By the end of the month all of Daniels County improved to (D3-Extreme) conditions.
To start September, ongoing drought conditions (D3-Extreme) were in place across the northeastern two thirds and the northwestern corner of Eastern Roosevelt County, while the southwestern third of Eastern Roosevelt County was in (D4-Exceptional) conditions. These conditions remained the same through the end of the month.
To start September, ongoing drought conditions were (D4-Exceptional) in the western three quarters of Richland County, with the far southeastern corner in (D2-Severe) and the rest of eastern Richland County in (D3-Extreme) conditions. By the second week of September the far southeastern corner had worsened to (D3-Extreme) conditions to match the rest of eastern Richland County while the western three quarters of the county remained in (D4-Exceptional) drought. These conditions remained the same the rest of the month.
To start September, ongoing drought conditions in most of Dawson County were at (D4-Exceptional) conditions, the exception being the far eastern tip of the county and that area remained in (D3-Extreme) drought. These conditions remained unchanged throughout all of September.
To start the month of September, ongoing drought conditions in the northeastern corner of Wibaux County were at (D2-Severe) conditions, the rest of the northern part of the county was in (D3-Extreme) conditions and the southern two thirds of the county were in (D4-Exceptional) conditions. On the second week of September, the whole northern third of Wibaux County was in (D3-Extreme) conditions, while the southern two thirds of the county remained in (D4-Exceptional) conditions. These conditions remained the same through the end of the month.
To start the month of September, ongoing drought conditions in the eastern two thirds of Prairie County were (D4-Exceptional) conditions, with the western third in (D3-Extreme) conditions. These conditions remained the same through the end of the month.
To start September, ongoing drought conditions in the southwestern half of western Roosevelt County including the western border with Valley County were at (D4-Exceptional) while the northeastern half of western Roosevelt County remained in (D3-Extreme) conditions. By the end of the month the northern two thirds of western Roosevelt County improved to (D3-Extreme) conditions while the southwestern third of western Roosevelt County remained at (D4-Exceptional) drought.
To start September, ongoing drought conditions in all but the southeastern corner of McCone County were in (D4-Exceptional) with the southeastern corner in (D3-Extreme) conditions. These conditions remained the same for the rest of the month.
To start September, ongoing drought conditions in the eastern half of Northern Valley County were at (D4-Exceptional) drought while the western half was in (D3-Extreme) conditions. By the end of the month, all of Northern Valley County had improved to (D3-Extreme) drought conditions.
To start the month of September, ongoing drought conditions in all but a little area of the north central portion of Central and Southern Valley County were at (D4-Exceptional) conditions while that little portion was in (D3-Extreme) drought. By the end of the month, the northeast corner of Central and Southern Valley County improved to (D3-Extreme) conditions, while the remaining area of Central and Southern Valley County remained in (D4-Exceptional) drought.
To start September, ongoing drought conditions in northern Garfield County around Fort Peck Lake were at (D4-Exceptional) conditions while the southeastern two thirds of Garfield County were in (D3-Extreme) drought. These conditions remained the same through the end of the month.
To start the month of September, ongoing drought conditions were at (D3-Extreme) for all but the extreme northwest corner of Northern Phillips County which remained in (D2-Severe). These conditions remained the same through the end of the month.
To start September, ongoing drought conditions were at (D4-Exceptional) in the eastern and southeastern three quarters of Central and Southeast Phillips County, with the western and northwestern quarter in (D3-Extreme) conditions. These conditions remained the same through the end of September.
To start September, ongoing drought conditions were at (D4-Exceptional) for the northern three quarters of Petroleum County, while the southern quarter of Petroleum County remained in (D3-Extreme) conditions. These conditions remained the same through the end of September.
To start September, ongoing drought conditions were at (D3-Extreme) conditions for all of the Little Rocky Mountains. These conditions remained the same through the end of September.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, September 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 980559, 981693, 984827, 984828, 984834, 984837, 984838, 984839, 984842, 984847, 984849, 984854, 984857, 984932, 984933, 984934.