Checking the live aurora model…
The aurora follows Earth's magnetic field, not the map grid. Green Bay sits at 53.4° geomagnetic latitude, and NOAA's table says the aurora reaches that line at Kp 7 — a G3 storm, which happens on ~130 days per 11-year solar cycle.
| Kp index | Reaches down to | How often |
|---|---|---|
| Kp 4 | 58.3° geomagnetic | quiet to unsettled conditions |
| Kp 5 | 56.3° geomagnetic | G1 · ~900 days per 11-year solar cycle |
| Kp 6 | 54.2° geomagnetic | G2 · ~360 days per 11-year solar cycle |
| Kp 7 | 52.2° geomagnetic | G3 · ~130 days per 11-year solar cycle |
| Kp 8 | 50.1° geomagnetic | G4 · ~60 days per 11-year solar cycle |
| Kp 9 | 48.1° geomagnetic | G5 · about 4 days per 11-year solar cycle |
Storm frequencies are NOAA's published figures for the G-scale, averaged over an 11-year solar cycle.
Even when the Kp is high enough, street lighting can hide a low, faint aurora. Our light pollution map starts on Green Bay and finds the darkest spots within driving distance:
Yes, but only during a geomagnetic storm. Green Bay sits at 53.4° geomagnetic latitude, so the aurora reaches it at a Kp index of 7 — a G3 storm, which NOAA records on ~130 days per 11-year solar cycle. The live Kp index and the three-day forecast are at the top of this page.
The aurora follows Earth's magnetic field, and the magnetic pole is not at the geographic pole — it sits near 80.7°N, 72.7°W. That is why Green Bay at 44.5° on the map behaves like 53.4° for the aurora. It also means places at the same map latitude can need very different Kp values: northern Europe sees the aurora far more easily than the same latitude in Siberia.
Activity usually peaks around local magnetic midnight, roughly 22:00–02:00, but a substorm can start any time it is dark. At this latitude the aurora normally appears low on the northern horizon, so you need a clear view north and as little light as possible.
Yes. A bright moon washes out a faint aurora the same way city lights do. The moon tile above shows tonight's phase and illumination — under 25% is a good dark sky, over 65% will hide anything but a strong display.
The Kp index, the three-day forecast and the OVATION aurora model come from the NOAA Space Weather Prediction Center — U.S. government works in the public domain, refreshed here every 30 minutes. The Kp threshold for Green Bay is calculated from its geomagnetic latitude using NOAA's published table. Cloud cover is not part of this page — check your local weather forecast too.