Montana, United States
Northern lights in Great Falls
Answer
Tonight
Darkness window open
Civil darkness has begun.
Observed 11:55 UTC, forecast 13:26 UTC, 91 min lead
Clock times in America/Denver
Valid 12:00 to 13:00 UTC
Storm level needed
Great Falls sits at 47.50N 111.30W in Montana, United States. The IGRF-14 centered dipole puts Great Falls at 54.3 degrees geomagnetic latitude, 6.8 degrees closer to the magnetic pole than its map latitude suggests. Great Falls sits at 54.3 degrees geomagnetic. The lowest NOAA storm level whose typical viewing latitude reaches it is G3 (Kp = 7). By SWPC's rule the average oval edge is overhead only at Kp 6.
"aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.)"
The nearest other Glow towns are Missoula (215 km), Lethbridge (269 km), Medicine Hat (286 km). Missoula sits 0.9 degrees lower on the dipole, Kp 7 against 6 here.
Approximate: SWPC calls its Kp to latitude rule an average, and a centered dipole can differ by a degree from fuller field models. How the storm level is matched
The year in darkness
Every night of 2026 at Great Falls has some civil darkness; the shortest month sample still has 6.6 hours. Every evening of the year at Great Falls clears Glow's dark-season bar of 4 hours of civil night between 18:00 and 06:00. Great Falls's longest night of the year, Dec 19, has 14 h 16 min of civil night.
Solar midnight at Great Falls, when the sun is lowest, falls at 00:20 on local clocks on December 15 and 01:26 on June 15. That is 20 min after midnight in December and 1 h 26 min after midnight in June, the gap set by daylight saving and the equation of time. So at Great Falls the darkest hour sits near the middle of SWPC's 10 PM to 2 AM window in winter.
Month by month
| Month | Night | Civil | Cloud | Clear dark | |
|---|---|---|---|---|---|
| Jan | 13.8 h | 11.3 h | 70% | 4.1 h | |
| Feb | 12.5 h | 10.1 h | 70% | 3.8 h | |
| Mar | 11.0 h | 8.6 h | 71% | 3.2 h | |
| Apr | 9.1 h | 6.4 h | 69% | 2.8 h | |
| May | 7.5 h | 3.9 h | 65% | 2.6 h | |
| Jun | 6.6 h | 1.4 h | 57% | 2.8 h | |
| Jul | 7.0 h | 2.9 h | 38% | 4.3 h | |
| Aug | 8.5 h | 5.5 h | 44% | 4.8 h | |
| Sep | 10.3 h | 7.8 h | 52% | 4.9 hbest | |
| Oct | 12.0 h | 9.6 h | 63% | 4.4 h | |
| Nov | 13.5 h | 11.1 h | 69% | 4.2 h | |
| Dec | 14.2 h | 11.7 h | 69% | 4.4 h |
By the 15th-of-the-month sample, December is the darkest month at Great Falls with 14.2 hours of civil night and June the lightest at 6.6. Across the year Great Falls gets 3,835 hours of civil night. Astronomical night at Great Falls, the sun 18 degrees or more below the horizon, lasts 11.7 hours on December 15.
NASA POWER's 2001 to 2020 all-hours climatology puts mean cloud amount for the 1 degree cell around Great Falls at 62% across the year, from 38% in July to 71% in March. In the months with at least 4 hours of civil night Great Falls averages 61%, against a median of 61% for Glow towns in United States.
Multiplying civil night by the clear share of the sky gives September the best score, 4.9 hours, ahead of August at 4.8. Great Falls's equinox months score 3.2 in March and 4.9 in September, the weeks SWPC links with larger storms.
Kp history
From 1996 to 2025, the GFZ Potsdam record shows a 3-hour Kp of 6 or more, the level that puts the average oval edge over Great Falls, on 3% of days. At Great Falls's level the share runs from 1% in December to 5% in October, while storm days with Kp 5 or more made up 10%.
Share of UTC days in each calendar month whose highest 3-hour Kp reached Kp 6. Kp history by year
Moon, next 30 nights
Over the 30 nights from Oct 1, the new moon falls on Oct 10 and the full moon on Oct 25, in America/Denver dates. 15 of the 30 nights at Great Falls have at least 2 moon-free dark hours inside 10 PM to 2 AM, and Oct 5 has the most at 4 h. Tonight Great Falls has 11 h 15 min of civil night, 2 h 3 min of it with the moon down.
- 1
65% lit
2.0 h
- 2
54% lit
3.2 h
- 3
42% lit
4.5 h
- 4
31% lit
5.9 h
- 5
21% lit
7.3 h
- 6
13% lit
8.6 h
- 7
7% lit
9.9 h
- 8
2% lit
11.2 h
- 9
0% lit
11.7 h
- 10
1% lit
11.8 h
- 11
3% lit
11.8 h
- 12
7% lit
11.8 h
- 13
13% lit
11.6 h
- 14
20% lit
10.9 h
- 15
28% lit
10.2 h
- 16
37% lit
9.3 h
- 17
46% lit
8.3 h
- 18
56% lit
7.1 h
- 19
65% lit
6.0 h
- 20
74% lit
4.8 h
- 21
82% lit
3.7 h
- 22
90% lit
2.5 h
- 23
95% lit
1.2 h
- 24
99% lit
0.0 h
- 25
100% lit
0.0 h
- 26
98% lit
0.0 h
- 27
94% lit
0.0 h
- 28
87% lit
0.8 h
- 29
78% lit
1.8 h
- 30
68% lit
3.1 h
Each cell is the night that starts on that date. Hours are civil-dark time with the moon below the horizon; the green rule scales with them. Green outline: new moon. Bone outline: full moon.
Within United States
Among the 3 Glow towns in Montana, Great Falls ranks 1st by dipole latitude against a regional median of 53.4 degrees, the highest of them. Among the 136 Glow towns in United States, Great Falls ranks 14th by dipole latitude against a national median of 51.5 degrees; Fairbanks sits highest at 65.7. On December 15 Great Falls gets 14.2 hours of civil night, 15th longest of 136 in United States, where the median is 13.8.
Questions
- Can you see the northern lights in Great Falls?
- Great Falls sits at 54.3 degrees geomagnetic. The lowest NOAA storm level whose typical viewing latitude reaches it is G3 (Kp = 7). By SWPC's rule the average oval edge is overhead only at Kp 6. Clear, dark sky over Great Falls still decides it.
- When is it dark enough in Great Falls?
- Every night at Great Falls has civil darkness. Tonight has 11 h 15 min, and December 15 has 14.2 hours.
- What is the best month for aurora in Great Falls?
- September, by civil night at Great Falls times the clear share of the sky from NASA POWER's 2001 to 2020 average.
- How cloudy is Great Falls in the dark months?
- About 61% mean cloud amount over Great Falls in the months with at least 4 hours of civil night, from NASA POWER's 2001 to 2020 all-hours climatology.
- How often is activity high enough for Great Falls?
- A 3-hour Kp of 6 or more, the level that puts the average oval edge overhead, occurred on 3% of days from 1996 to 2025 in the GFZ Potsdam record.
Nearby and related
Nearest Glow towns
Great Falls by month
Region and comparisons