Will you see the northern lights tonight?
Honest answer: it depends far more on where you are than on tonight’s headlines. The same storm that parks curtains over Winnipeg is invisible from Denver. This page checks NOAA’s live space-weather data, then tells you what the numbers mean for your city, without the raw-Kp overpromising that has aurora-app users staring at empty skies.
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With JavaScript on, this box pulls NOAA’s latest space-weather data: current Kp, whether a storm watch is up, and (if you share your location) the model’s aurora odds for your exact sky. Without it, the table below tells you what Kp your city needs; compare it against any Kp forecast.
What Kp actually is (and isn’t)
Kp is a 3-hour, planet-wide average of geomagnetic disturbance, on a 0-9 scale. It is genuinely useful: higher Kp means the auroral oval swells farther south. But it is not a tonight-guarantee, three ways: it’s global (one number for the whole planet, nothing about your sky), it’s 3-hourly (the peak may land while your sky is still bright or after you’ve gone to bed), and it’s often forecast (the real driver is solar wind that we only measure ~30-60 minutes before it arrives). Seeing aurora is four gates multiplied together (activity × darkness × your geomagnetic latitude × clouds), and any one of them can zero the night out.
What Kp does your city need?
Match your city (or the closest one) against the oval’s reach. The threshold is set by geomagnetic latitude: the magnetic pole sits over northern Canada, so the aurora reaches much farther south over central and eastern North America than over the West Coast or Europe.
| Kp reaches… | Horizon-visible down to (geomagnetic) | First becomes visible from, e.g. |
|---|---|---|
| Kp 0 | 57.5° | Anchorage, Fairbanks, Juneau, Winnipeg |
| Kp 1 | 55.5° | Grand Forks, Duluth, Marquette, Caribou |
| Kp 2 | 53.4° | Spokane, Missoula, Bismarck, Fargo |
| Kp 3 | 51.4° | Seattle, Bozeman, Billings, Madison |
| Kp 4 | 49.3° | Portland, Boise, Chicago, Cleveland |
| Kp 5 | 47.3° | — |
| Kp 6 | 45.2° | — |
| Kp 7 | 43.2° | — |
| Kp 8 | 41.1° | — |
| Kp 9 | 39.1° | — |
"Horizon-visible" means a glow low in the north, not curtains overhead; overhead needs roughly 2-3 more Kp points. Geomagnetic latitude is what matters, and it differs from map latitude by up to ~7° across North America (the magnetic pole leans toward Canada, which is why Boston out-performs Portland, Oregon despite being farther south on the map).
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Aurora by city
Alaska
Alberta
British Columbia
- Vancouver · needs ~Kp 2
Idaho
- Boise · needs ~Kp 4
Illinois
- Chicago · needs ~Kp 4
Maine
Manitoba
- Winnipeg · under the oval
Massachusetts
- Boston · needs ~Kp 3
Michigan
- Marquette · needs ~Kp 1
- Traverse City · needs ~Kp 2
- Grand Rapids · needs ~Kp 3
- Detroit · needs ~Kp 3
Minnesota
- Duluth · needs ~Kp 1
- Minneapolis · needs ~Kp 2
Montana
New Hampshire
- Concord · needs ~Kp 3
New York
North Dakota
- Bismarck · needs ~Kp 2
- Fargo · needs ~Kp 2
- Grand Forks · needs ~Kp 1
Northwest Territories
- Yellowknife · under the oval
Nova Scotia
- Halifax · needs ~Kp 2
Ohio
- Cleveland · needs ~Kp 4
Ontario
Oregon
- Portland · needs ~Kp 4
Pennsylvania
- Erie · needs ~Kp 4
Quebec
- Montreal · needs ~Kp 2
- Quebec City · needs ~Kp 1
Saskatchewan
Vermont
- Burlington · needs ~Kp 2
Washington
Wisconsin
Yukon
- Whitehorse · under the oval
Northern lights tonight FAQ
What Kp index do I need to see the northern lights?
It depends entirely on your geomagnetic latitude: there is no single number. Fairbanks needs essentially none; Winnipeg and Edmonton see aurora at Kp 2-3; Seattle and Minneapolis need about Kp 4-5; Chicago and Boston need a genuine storm at Kp 6+. The table on this page lists the threshold city by city, and each city page explains its own number.
Is Kp 5 enough to see the aurora where I live?
Kp 5 (a G1 storm) puts horizon-visible aurora down to about 47° geomagnetic latitude, roughly the northern tier of the US. But Kp is a 3-hour global average: a forecast Kp 5 doesn't mean your exact hours after dark hit Kp 5, or that your sky is clear. Treat Kp as 'the oval might reach me tonight', then check the live NOAA model odds, darkness, and clouds, which is what this site's per-city check does.
Why does my aurora app alert me and then I see nothing?
Because most apps alert on raw planetary Kp, which ignores everything local: whether it's dark where you are, whether your geomagnetic latitude is far enough north, whether it's cloudy, and whether the 3-hour global window overlaps your night at all. A real verdict is activity × darkness × geometry × clouds; any one of them can zero out the others.
What months are best for seeing the northern lights?
September through March in the mid-latitudes: long dark nights plus the equinox effect (geomagnetic storms statistically cluster around late September and late March). At far-north latitudes like Fairbanks or Yellowknife, late August through mid-April; midsummer skies there never get dark enough regardless of activity.