Aurora Visibility - Aurora Forecast
Aurora Visibility answers one practical question: is it worth going outside to look for the northern lights tonight? It combines live space-weather data from the NOAA Space Weather Prediction Center with local cloud cover from Open-Meteo and turns them into a single visibility percentage for where you are.
Aurora apps often show either the geomagnetic activity or the weather, but you need both. A strong storm is useless under thick cloud, and a clear sky does nothing if the aurora oval is far to the north. This page puts the Kp index, the modelled aurora probability at your location, cloud cover, darkness and a 24-hour forecast on one screen.
It runs in your browser with no account. Allow location access when your browser asks, and the forecast is calculated for your position.
The app runs entirely in your browser. What you enter is saved only on this device.
How to use Aurora Visibility
- Allow location. When the browser asks to share your location, choose Allow. If you decline or don't answer within about 15 seconds, the app shows Reykjavik, Iceland as a sample location instead.
- Read the visibility score. The large ring on Home shows the current visibility percentage and a label from Low to Excellent. Below it are the Kp index, cloud cover, the current weather and whether it is day or night.
- Check the best time tonight. The Best Time Tonight card names the dark hour with the highest score, when at least one hour scores above 20%. Otherwise it says there is no optimal time.
- Look at the 24-hour forecast. Open the Forecast tab for a chart of predicted visibility over the next 24 hours, sunrise and sunset times, hours of darkness and an hourly breakdown.
- Open the map. The Map tab shows your position with the current Kp level, visibility and cloud cover. The button at the top right re-centres the map on you.
- Refresh. Tap the refresh button at the top of Home to download the latest NOAA and weather data.
Features
- Visibility percentage combining aurora probability, cloud cover and darkness
- Current planetary Kp index from NOAA SWPC
- Aurora probability for your position from the NOAA OVATION model
- Cloud cover, temperature and weather from Open-Meteo
- Best viewing hour tonight
- 24-hour visibility chart with hourly details
- Sunrise, sunset and hours of darkness
- Map of your location with the current activity level
- Interface in many languages
How to read an aurora forecast
The Kp index
Kp is a 0 to 9 scale of global geomagnetic disturbance, measured over three-hour periods. Higher numbers mean the auroral oval, the ring of aurora around the magnetic pole, grows brighter and expands toward the equator. Very roughly, Kp 1 to 3 keeps the aurora over high-latitude places such as northern Norway, Iceland, Fairbanks or Yellowknife; Kp 5 and above is a geomagnetic storm and can bring displays to mid-latitudes; Kp 7 or more is rare and widely visible.
Kp is a global average, so it is a guide rather than a promise for your exact town.
Probability at your location
NOAA's OVATION model estimates, on a world grid, how likely aurora is overhead in the next half hour or so. Aurora Visibility uses the grid point nearest to you. Remember that aurora low on the horizon can be seen from a few hundred kilometres away from where it is overhead, so a small number does not always mean nothing is visible to the north.
Clouds and darkness matter most
The aurora happens about 100 km up, far above the weather. Any thick cloud hides it completely, which is why the score multiplies the aurora probability by the share of clear sky. Daylight drowns it out too, so hours between sunset and sunrise count fully and daylight hours are heavily discounted. In summer at high latitudes the sky may never get dark enough.
Moonlight and city lights also wash out faint aurora. Driving even 20 minutes away from streetlights can make a big difference.
Practical tips for watching
Face the pole: north in the Northern Hemisphere. Activity often peaks within a couple of hours of local midnight, but displays can come and go in bursts, so patience pays. Let your eyes adapt for 15 to 20 minutes and avoid looking at your phone screen at full brightness.
Phone cameras in night mode often pick up colour that the eye sees as grey-white. Dress for the cold, tell someone where you are going, and stay safe on icy roads.
Frequently asked questions
Where does the data come from?
The Kp index, Kp forecast and aurora probability come from the NOAA Space Weather Prediction Center. Cloud cover, temperature, weather and sunrise/sunset come from Open-Meteo. Your browser downloads them directly when the page opens or when you refresh.
Why does it show Reykjavik?
That appears when the browser has no location: you declined the permission, didn't answer the prompt, or your device couldn't determine a position. Allow location for this site in your browser settings and reload.
Is my location stored or sent anywhere?
Your coordinates are used to request the weather forecast for that point from Open-Meteo and to pick the nearest NOAA grid point. There is no account, and nothing is uploaded to this site.
Can it alert me when the aurora is likely?
Not on the web, because a web page can't check in the background after the tab is closed. The iPhone and Android apps include optional notifications.
Why is the score low when the Kp is high?
Usually because of cloud cover or daylight, or because you are far from the auroral oval. All three have to line up.
What is different from the phone app?
The apps add background alerts and show ads that a subscription removes. The web version has no ads or purchases and no notifications.
Limitations of the web version
- No notifications or background checks
- Location comes only from the browser; there is no manual city search
- The map is a simple location view, not an aurora oval overlay
- Forecasts are only as good as the NOAA and weather models behind them
Disclaimer
Aurora forecasts are estimates and the aurora is notoriously hard to predict. The score is a guide only. Check local weather and road conditions and take care outdoors at night.
Phone app
Aurora Visibility is also available as an app for phones and tablets: