Northern Lights Forecast — USA Tonight
Live Kp index · Bz field · City-by-city visibility · Updated every 2 minutes
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Kp Index · Now
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Bz (IMF) · Now
—nT
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Solar Wind Speed
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US Cities — Aurora Visibility Tonight
Alaska
Upper Midwest & Northern Plains
Great Lakes & Midwest Cities
Mountain West
Northeast
Deep South & West Coast — Extreme Storms Only
Aurora Visibility by Kp — USA
| Kp 0–1 | Fairbanks, Utqiagvik, most of Alaska — aurora likely overhead |
| Kp 4–5 | Duluth, Bismarck, Fargo, Billings, Helena, northern Michigan |
| Kp 6 (G2) | Minneapolis, Chicago, Omaha, Buffalo, Portland (ME), Salt Lake City |
| Kp 7 (G3) | Indianapolis, Kansas City, St. Louis, Denver — look north on horizon |
| Kp 8–9 (G4–G5) | Rare — Dallas, Austin, Atlanta, and Southern California have all seen aurora during the strongest storms on record |
Tips for Aurora Viewing in the USA
- Get away from city lights — light pollution is the biggest barrier for most US viewers
- Watch the Bz component: sustained negative Bz (southward) is the key trigger
- Peak viewing hours are typically 10 PM – 2 AM local time
- US aurora season runs September through March when nights are longest
- Check your local cloud forecast — clear skies are essential
- Below the northern-tier states, don't plan a trip around it — just watch the forecast and be ready
What Is the Kp Index?
The Kp index measures global geomagnetic activity on a scale of 0–9, updated every 3 hours by NOAA. The higher the Kp, the further south aurora becomes visible. A Kp of 5 marks a G1 geomagnetic storm. Real-time data on this page comes directly from NOAA's Space Weather Prediction Center.
Why Bz Matters
The Bz component of the interplanetary magnetic field is the single most important aurora predictor. When Bz turns negative (southward), it connects with Earth's magnetic field and allows solar energy in — driving geomagnetic storms and aurora. A sustained Bz of −10 nT or lower significantly increases aurora chances even at moderate Kp levels.