The aurora borealis isn't only for Alaska. During geomagnetic storms it reaches far into the lower 48 — and cameras record it long before your eyes see color.
Understanding Kp
The Kp index (0–9) measures global geomagnetic activity. Higher Kp pushes the auroral oval toward the equator:
- Kp 3–4: visible on the horizon from northern Minnesota, Michigan's Upper Peninsula, northern Maine and Montana's Hi-Line.
- Kp 5–6: the northern tier of states, often as far south as Washington, the Dakotas and New York.
- Kp 7+: strong storms; aurora possible across much of the country, occasionally as far south as Colorado or the mid-Atlantic.
What matters is your geomagnetic latitude, not just geography. Each state aurora page shows the approximate Kp needed for its cities and a live Kp forecast.
Forecast tools
- 3-day Kp forecast (NOAA SWPC) for planning.
- 30-minute OVATION forecast for real-time decisions.
- Solar wind Bz: a sustained southward (negative) Bz often precedes the best displays.
Storms tend to peak around local midnight, but substorms can erupt any time after dark.
Where to go
- Get away from city lights with an unobstructed northern horizon: lakeshores, prairies, ridges.
- The darker the sky, the fainter the aurora you can catch — check the Bortle estimates on location pages.
- Lakes add reflections, which double the color.
Camera settings
- ISO 1600–3200 (higher for faint displays).
- Aperture f/1.4–f/2.8.
- Shutter 2–15 seconds: shorter for fast-moving curtains to keep structure, longer for faint glows.
- White balance ~3500–4000 K.
- Focus manually on a bright star.
Tips
- Take test shots whenever Kp is near your threshold — a faint green or red band on the LCD is often invisible to the eye.
- Moonlight lights the foreground but hides faint aurora; strong storms are still worth it.
- Shoot vertical frames when pillars rise high, and time-lapses when it dances.
- Dress for long, cold waits and keep spare batteries warm.
About 1 min read · Updated 2026-10-20