Wisconsin, United States
Northern lights in Janesville
Answer
Tonight
Waiting on darkness
It is not civil-dark yet. The next dusk is listed below.
Observed 11:49 UTC, forecast 13:20 UTC, 91 min lead
Clock times in America/Chicago
Valid 12:00 to 13:00 UTC
Storm level needed
Janesville sits at 42.68N 89.02W in Wisconsin, United States. The IGRF-14 centered dipole puts Janesville at 51.5 degrees geomagnetic latitude, 8.8 degrees closer to the magnetic pole than its map latitude suggests. Janesville sits at 51.5 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 8.
"aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.)"
The nearest other Glow towns are Rockford (46 km), Madison (53 km), Waukesha (74 km). Rockford sits 0.4 degrees lower on the dipole and needs the same Kp.
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 Janesville has some civil darkness; the shortest month sample still has 7.4 hours. Every evening of the year at Janesville clears Glow's dark-season bar of 4 hours of civil night between 18:00 and 06:00. Janesville's longest night of the year, Dec 18, has 13 h 48 min of civil night.
Solar midnight at Janesville, when the sun is lowest, falls at 23:51 on local clocks on December 15 and 00:56 on June 15. That is 9 min before midnight in December and 56 min after midnight in June, the gap set by daylight saving and the equation of time. So at Janesville 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 | 13.4 h | 11.2 h | 67% | 4.5 h | |
| Feb | 12.3 h | 10.2 h | 64% | 4.4 h | |
| Mar | 11.0 h | 8.8 h | 63% | 4.1 h | |
| Apr | 9.5 h | 7.0 h | 62% | 3.6 h | |
| May | 8.2 h | 5.2 h | 63% | 3.0 h | |
| Jun | 7.4 h | 4.0 h | 56% | 3.3 h | |
| Jul | 7.8 h | 4.6 h | 48% | 4.1 h | |
| Aug | 9.0 h | 6.4 h | 49% | 4.6 h | |
| Sep | 10.5 h | 8.2 h | 47% | 5.6 hbest | |
| Oct | 11.9 h | 9.7 h | 59% | 4.9 h | |
| Nov | 13.2 h | 10.9 h | 64% | 4.8 h | |
| Dec | 13.8 h | 11.4 h | 70% | 4.1 h |
By the 15th-of-the-month sample, December is the darkest month at Janesville with 13.8 hours of civil night and June the lightest at 7.4. Across the year Janesville gets 3,892 hours of civil night. Astronomical night at Janesville, the sun 18 degrees or more below the horizon, lasts 11.4 hours on December 15.
NASA POWER's 2001 to 2020 all-hours climatology puts mean cloud amount for the 1 degree cell around Janesville at 59% across the year, from 47% in September to 70% in December. In the months with at least 4 hours of civil night Janesville averages 59%, 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, 5.6 hours, ahead of October at 4.9. Janesville's equinox months score 4.1 in March and 5.6 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 8 or more, the level that puts the average oval edge over Janesville, on 0% of days. At Janesville's level the share runs from 0% in February to 1% in November, 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 8. 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/Chicago dates. 15 of the 30 nights at Janesville have at least 2 moon-free dark hours inside 10 PM to 2 AM, and Oct 5 has the most at 4 h. Tonight Janesville has 11 h 16 min of civil night, 2 h 25 min of it with the moon down.
- 1
65% lit
2.4 h
- 2
54% lit
3.5 h
- 3
43% lit
4.8 h
- 4
32% lit
6.1 h
- 5
22% lit
7.4 h
- 6
13% lit
8.6 h
- 7
7% lit
9.9 h
- 8
2% lit
11.1 h
- 9
0% lit
11.6 h
- 10
0% lit
11.7 h
- 11
3% lit
11.7 h
- 12
7% lit
11.7 h
- 13
13% lit
11.2 h
- 14
20% lit
10.6 h
- 15
28% lit
9.8 h
- 16
36% lit
8.9 h
- 17
46% lit
7.9 h
- 18
55% lit
6.8 h
- 19
65% lit
5.8 h
- 20
74% lit
4.7 h
- 21
82% lit
3.6 h
- 22
89% lit
2.5 h
- 23
95% lit
1.3 h
- 24
99% lit
0.1 h
- 25
100% lit
0.0 h
- 26
98% lit
0.0 h
- 27
94% lit
0.1 h
- 28
87% lit
1.0 h
- 29
79% lit
2.1 h
- 30
68% lit
3.3 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 11 Glow towns in Wisconsin, Janesville ranks 10th by dipole latitude against a regional median of 51.9 degrees; Eau Claire sits highest at 53.4. Among the 136 Glow towns in United States, Janesville ranks 73rd by dipole latitude against a national median of 51.5 degrees; Fairbanks sits highest at 65.7. On December 15 Janesville gets 13.8 hours of civil night, 52nd longest of 136 in United States, where the median is 13.8.
Questions
- Can you see the northern lights in Janesville?
- Janesville sits at 51.5 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 8. Clear, dark sky over Janesville still decides it.
- When is it dark enough in Janesville?
- Every night at Janesville has civil darkness. Tonight has 11 h 16 min, and December 15 has 13.8 hours.
- What is the best month for aurora in Janesville?
- September, by civil night at Janesville times the clear share of the sky from NASA POWER's 2001 to 2020 average.
- How cloudy is Janesville in the dark months?
- About 59% mean cloud amount over Janesville 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 Janesville?
- A 3-hour Kp of 8 or more, the level that puts the average oval edge overhead, occurred on 0% of days from 1996 to 2025 in the GFZ Potsdam record.
Nearby and related
Nearest Glow towns
Janesville by month
Region and comparisons