Northern lights in Montana tonight
The aurora reaches Montana at about Kp 5.7 in the far north of the state and Kp 6.7 at its southern edge. SWPC's highest forecast Kp over the next three days is 2, in the 03-06 UTC block on Mon, Sep 21. Not tonight. The forecast Kp of 2 is well below what it takes for the aurora to reach this far south.
From NOAA’s Space Weather Prediction Center, read Sep 20, 15:00 UTC.
The oval right now
NOAA’s OVATION model: the chance of aurora overhead 30 to 90 minutes from now, valid Sep 20, 15:56 UTC. Green is a low chance, red a high one.
Rain and snow mean cloud, and cloud is the last thing between a forecast aurora and the sky you are standing under. Each town page carries that town’s own sky cover forecast for the dark hours.
Open the live map with the aurora forecast
Aurora forecast from NOAA’s Space Weather Prediction Center. Original at SWPC
Tonight at Plentywood
The most poleward town in Montana with a page, and the first place in the state an aurora reaches. Cloud cover is on each town’s own page.
No tonight
Not tonight. The forecast Kp of 2 is well below what it takes for the aurora to reach this far south.
- The aurora reaches this place at about Kp 5.7, which is 56 degrees geomagnetic latitude on NOAA's storm scales.
- SWPC forecasts a highest Kp of 2 (2.00) during tonight's dark hours: quiet.
- The moon is waxing gibbous, 71% lit, and up for part of the dark hours.
Towns best placed in Montana
The 24 most poleward of the 157 towns in Montana with a page. Each page gives tonight’s chance there, the darkness, the moon and that town’s own cloud forecast.
- PlentywoodSheridan County · population 1,923 · 56.3° geomagneticKp 5.7
- ScobeyDaniels County · population 1,033 · 56.2° geomagneticKp 5.8
- CulbertsonRoosevelt County · population 815 · 55.7° geomagneticKp 5.9
- ChinookBlaine County · population 1,228 · 55.6° geomagneticKp 5.9
- HarlemBlaine County · population 822 · 55.6° geomagneticKp 5.9
- PoplarRoosevelt County · population 871 · 55.6° geomagneticKp 5.9
- Fort Belknap AgencyBlaine County · population 1,293 · 55.6° geomagneticKp 5.9
- Havre NorthHill County · population 716 · 55.5° geomagneticKp 5.9
- MaltaPhillips County · population 1,963 · 55.5° geomagneticKp 5.9
- HavreHill County · population 9,834 · 55.5° geomagneticKp 5.9
- GlasgowValley County · population 3,414 · 55.5° geomagneticKp 5.9
- Wolf PointRoosevelt County · population 2,850 · 55.5° geomagneticKp 5.9
- FairviewRichland County · population 962 · 55.4° geomagneticKp 5.9
- ChesterLiberty County · population 883 · 55.3° geomagneticKp 5.9
- Cut BankGlacier County · population 3,002 · 55.3° geomagneticKp 5.9
- SidneyRichland County · population 6,828 · 55.3° geomagneticKp 5.9
- ShelbyToole County · population 3,268 · 55.2° geomagneticKp 6
- EurekaLincoln County · population 1,074 · 55.2° geomagneticKp 6
- North BrowningGlacier County · population 2,408 · 55.2° geomagneticKp 6
- BrowningGlacier County · population 1,027 · 55.2° geomagneticKp 6
- South BrowningGlacier County · population 1,785 · 55.1° geomagneticKp 6
- Big SandyChouteau County · population 593 · 55.1° geomagneticKp 6
- HaysBlaine County · population 843 · 55.1° geomagneticKp 6
- TregoLincoln County · population 541 · 55.1° geomagneticKp 6
Every town in Montana with a page
157 towns at 48 degrees geomagnetic latitude or higher, which a strong storm reaches. The figure after each is the Kp it takes there.
A
B
- Baker Kp 6.2
- Belgrade Kp 6.5
- Belt Kp 6.2
- Big Sandy Kp 6
- Big Sky Kp 6.6
- Big Timber Kp 6.4
- Bigfork Kp 6.1
- Billings Kp 6.4
- Black Eagle Kp 6.1
- Bonner-West Riverside Kp 6.3
- Boulder Kp 6.4
- Bozeman Kp 6.5
- Bridger Kp 6.5
- Broadus Kp 6.4
- Browning Kp 6
- Busby Kp 6.4
- Butte Kp 6.5
C
- Carlton Kp 6.4
- Cascade Kp 6.2
- Chester Kp 5.9
- Chinook Kp 5.9
- Choteau Kp 6.1
- Churchill Kp 6.5
- Circle Kp 6
- Clancy Kp 6.4
- Clinton Kp 6.3
- Colstrip Kp 6.4
- Columbia Falls Kp 6
- Columbus Kp 6.5
- Conrad Kp 6
- Coram Kp 6
- Corvallis Kp 6.4
- Crow Agency Kp 6.4
- Culbertson Kp 5.9
- Cut Bank Kp 5.9
D
- Darby Kp 6.5
- Deer Lodge Kp 6.4
- Dillon Kp 6.6
E
- East Helena Kp 6.3
- East Missoula Kp 6.3
- Ekalaka Kp 6.3
- Ennis Kp 6.6
- Eureka Kp 6
- Evergreen Kp 6.1
F
- Fairfield Kp 6.1
- Fairview Kp 5.9
- Florence Kp 6.4
- Forsyth Kp 6.3
- Fort Belknap Agency Kp 5.9
- Fort Benton Kp 6.1
- Four Corners Kp 6.5
- Frenchtown Kp 6.3
G
- Gallatin Gateway Kp 6.5
- Gardiner Kp 6.6
- Glasgow Kp 5.9
- Glendive Kp 6.1
- Great Falls Kp 6.1
H
- Hamilton Kp 6.5
- Hardin Kp 6.4
- Harlem Kp 5.9
- Harlowton Kp 6.3
- Havre Kp 5.9
- Havre North Kp 5.9
- Hays Kp 6
- Heart Butte Kp 6
- Helena Kp 6.3
- Helena Valley Northeast Kp 6.3
- Helena Valley Northwest Kp 6.3
- Helena Valley Southeast Kp 6.3
- Helena Valley West Central Kp 6.3
- Helena West Side Kp 6.3
- Hot Springs Kp 6.2
- Hungry Horse Kp 6
- Hysham Kp 6.3
J
K
- Kalispell Kp 6.1
- King Arthur Park Kp 6.5
L
- Lakeside Kp 6.1
- Lame Deer Kp 6.4
- Laurel Kp 6.4
- Lewistown Kp 6.2
- Libby Kp 6.1
- Lincoln Kp 6.3
- Livingston Kp 6.5
- Lockwood Kp 6.4
- Lolo Kp 6.3
M
- Malmstrom Air Force Base Kp 6.1
- Malta Kp 5.9
- Manhattan Kp 6.5
- Marion Kp 6.1
- Martin City Kp 6
- Miles City Kp 6.2
- Missoula Kp 6.3
- Montana City Kp 6.3
- Muddy Kp 6.4
N
- North Browning Kp 6
O
- Orchard Homes Kp 6.3
P
- Pablo Kp 6.2
- Park City Kp 6.5
- Philipsburg Kp 6.4
- Pinesdale Kp 6.4
- Pioneer Junction Kp 6.1
- Plains Kp 6.2
- Plentywood Kp 5.7
- Polson Kp 6.2
- Poplar Kp 5.9
- Pray Kp 6.5
- Pryor Kp 6.5
R
S
- Saint Ignatius Kp 6.2
- Scobey Kp 5.8
- Seeley Lake Kp 6.3
- Shelby Kp 6
- Shepherd Kp 6.4
- Sheridan Kp 6.6
- Sidney Kp 5.9
- Somers Kp 6.1
- South Browning Kp 6
- South Hills Kp 6.3
- Stanford Kp 6.2
- Stevensville Kp 6.4
- Sun Prairie Kp 6.1
- Superior Kp 6.3
T
- Terry Kp 6.1
- The Silos Kp 6.4
- Thompson Falls Kp 6.2
- Three Forks Kp 6.5
- Townsend Kp 6.4
- Trego Kp 6
- Troy Kp 6.1
U
- Ulm Kp 6.2
V
- Valier Kp 6
- Vaughn Kp 6.1
- Victor Kp 6.4
- Virginia City Kp 6.6
W
- Walkerville Kp 6.5
- Warm Springs Kp 6.4
- West Glendive Kp 6.1
- West Yellowstone Kp 6.7
- White Haven Kp 6.1
- White Sulphur Springs Kp 6.3
- Whitefish Kp 6
- Whitehall Kp 6.5
- Wibaux Kp 6.1
- Winnett Kp 6.2
- Wolf Point Kp 5.9
- Woods Bay Kp 6.1
- Worden Kp 6.4
- Wye Kp 6.3
How far south each storm level reaches
NOAA’s space weather scales state the geomagnetic latitude each level of geomagnetic storm reaches, and the places its aurora has been seen from. The geographic latitudes are those lines converted with the geomagnetic dipole; the aurora sits low on the northern horizon there, and overhead far poleward of it.
| Storm | Geomagnetic | Central US | Eastern US | Northern Europe | NOAA says the aurora |
|---|---|---|---|---|---|
| G1 MinorKp 5 | 60° | 52°N | 51°N | 61°N | commonly visible at high latitudes: northern Michigan and Maine |
| G2 ModerateKp 6 | 55° | 47°N | 46°N | 56°N | has been seen as low as New York and Idaho |
| G3 StrongKp 7 | 50° | 42°N | 41°N | 51°N | has been seen as low as Illinois and Oregon |
| G4 SevereKp 8 | 45° | 37°N | 36°N | 45°N | has been seen as low as Alabama and northern California |
| G5 ExtremeKp 9 | 40° | 32°N | 31°N | 40°N | has been seen as low as Florida and southern Texas |
Source: NOAA space weather scales, swpc.noaa.gov/noaa-scales-explanation. Below Kp 5 the oval contracts more slowly; this section runs the line from 66 degrees geomagnetic at Kp 0 to the scale’s 60 degrees at Kp 5.
Kp by 3-hour block
SWPC’s planetary K index forecast, three days ahead. Kp is a single number for the whole planet, from magnetometers around the world, on a scale of 0 to 9 in thirds.
| Block (UTC) | Kp | Level | Seen from | Central US |
|---|---|---|---|---|
| 1.00 | Quiet | 65° geomag. | 57°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 2.00 | Quiet | 64° geomag. | 55°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 0.67 | Quiet | 65° geomag. | 57°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.33 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N | |
| 1.67 | Quiet | 64° geomag. | 56°N |
The forecast is for the planet, not for your sky. A block at Kp 5 means the field is disturbed enough for the aurora to reach 60 degrees geomagnetic somewhere along the night side; whether you see it depends on being on the night side, on darkness, and on the clouds.
Other states with aurora pages
- Alaska
- Colorado
- Connecticut
- Delaware
- District of Columbia
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Missouri
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New York
- North Dakota
- Ohio
- Oregon
- Pennsylvania
- Rhode Island
- South Dakota
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
What this means
Each place is placed by its geomagnetic latitude, measured from the geomagnetic dipole pole, and compared with the reach NOAA states for each storm level on its space weather scales: G1 (Kp 5) about 60 degrees geomagnetic, G2 55, G3 50, G4 45, G5 (Kp 9) 40. Reading that backwards gives the Kp a place needs. Below Kp 5 the oval contracts more slowly and the line runs from 66 degrees at Kp 0 to 60 at Kp 5.
The forecasts have different horizons and the pages keep them apart: OVATION is the only thing that knows whether an aurora is out now, and it reaches 30 to 90 minutes ahead; the planetary Kp forecast runs three days; the 27-day outlook names likely active days and is not a forecast of any one night. None of them knows the clouds, which is why a town page reads its own forecast for those.
Sources
From NOAA’s Space Weather Prediction Center: the OVATION aurora forecast, the planetary K index forecast, the 3-day forecast, the 27-day outlook, its watches, warnings and alerts, and the real-time solar wind. Read Sep 20, 15:00 UTC.