Aurora forecasts, explained
To see the northern or southern lights you need three things at once: the aurora oval reaching your latitude, a dark sky and no clouds. This map shows the first two live from NOAA data; the sky you have to check yourself.
What is the Kp index and what does it mean for aurora?
The Kp index (planetary K index) runs from 0 to 9 and measures how disturbed Earth’s magnetic field is worldwide. It is a 3-hour index derived from ground-based magnetometers; this page reads NOAA SWPC’s planetary K-index feed, which gives one value per 3-hour interval. As a rough guide: Kp 1–2 — aurora close to the Arctic and Antarctic circles. Kp 3–4 — northern Norway, Iceland, northern Canada and Alaska. Kp 5 (G1 storm) — northern Scotland and southern Alaska may see it. Kp 7 (G3) — down to about 50° latitude, which includes Belgium, the Netherlands and the northern US. Kp 9 (G5) — much of Europe and the US. The dashed yellow line on the map uses a simple approximation of the oval’s edge: about 66.5° − 2.4 × Kp latitude.
Why is IMF Bz more important than Kp for predicting aurora?
Kp is a 3-hour index, so it describes what has already happened. IMF Bz is the north–south component of the magnetic field carried by the solar wind, measured minute by minute at the L1 point, about 1.5 million km sunward of Earth. When Bz turns southward (negative), the solar wind field connects with Earth’s magnetic field (dayside reconnection) and energy floods into the magnetosphere, which drives aurora. A sustained Bz of about −10 nT or lower usually produces visible aurora at 60° and higher. Bz can flip from +5 to −20 nT within minutes, so watching it gives you notice before Kp rises. Because the solar wind takes time to travel from L1 to Earth, a reading there gives roughly 15–60 minutes of warning, depending on solar wind speed. This page reads NOAA SWPC’s real-time solar wind feed, which comes from DSCOVR, with ACE as backup.
What is the NOAA Ovation aurora oval?
OVATION Prime is NOAA’s empirical aurora model. It takes real-time solar wind measurements from L1 and turns them into a short-term forecast: the probability of aurora at every point of a 1° latitude/longitude grid, for both the northern and southern hemisphere. This page downloads that grid (ovation_aurora_latest.json) on every refresh and paints each cell with 3% or more onto the map as a soft glow; the Min prob slider hides cells below the value you choose. It is the same model behind NOAA’s own aurora forecast images, here as a layer you can zoom and pan. Clicking the map gives the value of the nearest grid point.
Why does aurora need to be on the night side?
The auroral oval is there day and night, but daylight drowns out its faint glow. You need a dark sky: bright displays show up once the sun is well below the horizon, faint ones need full astronomical darkness (sun more than 18° below the horizon). The shaded area on the map is everywhere the sun is below the horizon right now, redrawn every minute, so it includes twilight: treat its edge as the earliest possible moment, not the best one. The ideal spot is under or poleward of the oval’s equatorward edge, well inside the shaded area, with a clear sky.
What are the best camera settings for aurora photography?
Aurora photography depends on display brightness, which scales with Kp. General rules: use your widest aperture lens (f/1.4–f/2.8), shoot in RAW not JPEG (vastly more editing latitude), and use a remote shutter release to avoid camera shake. Shutter speed is limited by the 500 Rule (500 ÷ focal length = max seconds before star trailing) — at 24mm, that's ~20 seconds. At Kp 7+, aurora moves fast and shorter exposures (5–10s) capture detail better. Focus manually to infinity — autofocus fails in low light. Set white balance to 3500–4500K (tungsten) to preserve the aurora's green colour in JPEGs; in RAW, adjust in post.
How often does this page update?
The page fetches all six NOAA SWPC feeds together every 3 minutes, and the night shading is redrawn every minute. That is not how often the values themselves change: the Kp index has one value per 3-hour interval, the OVATION oval is recalculated by NOAA every few minutes, and the solar wind and IMF data have 1-minute resolution. NOAA storm watches, warnings and alerts appear in the alert list on the next refresh after they are issued. The Kp chart shows the last 27 values, about 81 hours of activity.
What's the difference between a G1, G2, G3 storm?
NOAA's G-scale rates geomagnetic storms from G1 (minor, Kp 5) to G5 (extreme, Kp 9). G1: aurora at 60°+ (northern tip of Scandinavia, Alaska, Canada). Weak power grid fluctuations. G2 (Kp 6): aurora at 55°+ (southern Scandinavia, northern UK, northern US). G3 (Kp 7): aurora at 50°+ (Belgium, Netherlands, central US). Intermittent GPS degradation. G4 (Kp 8): aurora at 45°+ (central Europe, southern US). Widespread power grid problems possible. G5 (Kp 9): aurora at 40°+ (southern Europe, Mexico). The March 1989 G5 storm caused a 9-hour Quebec blackout. The May 2024 G5 storm produced aurora visible as far south as Spain and Florida.
Can I see the northern lights tonight?
Check three things on the map above: (1) does the aurora oval — or the yellow Kp visibility ring — reach down to your latitude, (2) is your location on the dark side of the day/night terminator, and (3) is your sky clear? Click your location (or use ◎ My Location) to get the OVATION aurora probability for that spot right now. Then watch IMF Bz: when it swings strongly southward (negative), you have roughly 15–60 minutes warning that activity is about to intensify — that is your cue to get outside.
What Kp do I need to see aurora in the UK, Belgium, Germany or the US?
Rough guide: northern Scandinavia, Iceland, Alaska, Canada — Kp 1–3 (most clear dark nights). Scotland, southern Norway — Kp 5 (G1 storm). Northern England, Denmark, northern Germany — Kp 6–7. Belgium, the Netherlands, central Germany — Kp 7–8 (G3–G4, a few nights per year near solar maximum). Northern US states — Kp 5–7. Spain, Italy, southern US — only extreme Kp 9 (G5) events like May 2024. The dashed yellow line on the map shows the reach at the current Kp, the orange line at Kp + 2.
Does this map show the southern lights (aurora australis)?
Yes. The NOAA Ovation model covers both hemispheres and the map draws both auroral ovals. Southern-hemisphere winter (June–August) is peak aurora-australis season for Tasmania, southern New Zealand and Antarctica — switch the view to South to fly straight there, and the same Kp/Bz physics applies.
Where does the data come from?
All space-weather data is fetched by your browser from public NOAA Space Weather Prediction Center feeds on services.swpc.noaa.gov: the planetary K index, the Kp forecast, the real-time solar wind plasma and magnetometer data, the OVATION aurora grid and the alert list. When you click the map, the coordinates are sent to BigDataCloud’s free reverse-geocoding service to show a place name, and the base map tiles come from Esri. ◎ My Location uses your browser’s location permission; the position is only used on the page and is not saved.
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