Aurora Window
Early accessUS, UK and EuropeFree app
A clear go or no go for the aurora tonight, from NOAA Kp and darkness.
Early access. The app works in your browser today; the Android app follows when enough people ask for it.
A clear go or no go for the aurora tonight, from NOAA Kp and darkness.
Early access. The app works in your browser today; the Android app follows when enough people ask for it.
Aurora Window gives you a clear answer for tonight: go, maybe or no go. It combines the NOAA Kp forecast with how dark it gets at your place and how far you are from the magnetic pole, and shows the reasons behind every answer.
How it works
Real screens from the app, filled with example data.
Pick a place and see Go, Maybe or No go for tonight, with a plain sentence under it. The Kp forecast comes live from NOAA, and example places carry a label.
Every answer lists when it is dark enough, the highest Kp while it is dark, how bright the moon is, and that clouds are not checked. In the example, Tromsø sits at magnetic latitude 67.5°.
Bars show measured and forecast Kp, coloured by storm level. Dashed lines mark the Kp your place needs for aurora overhead and low on the horizon.
Save your town, a cabin or a trip and see the answer for each tonight. In the example, Edinburgh sits at magnetic latitude 58.1°, further from the aurora than Tromsø.
Turn on alerts and pick a Kp level, or let the app choose the level your place needs. Alerts only come for dark hours and follow the newest forecast.
Search the built in list of cities and aurora spots, use your location once, or type the coordinates of a dark sky spot.
Try it now
This is the real app running in your browser, with nothing to install. Tap around, type your own numbers and see what you get. What you enter stays in this browser.
Reminders work only in the phone app.
What it does
Pick a place and see one word for tonight, with a plain sentence under it. Go means the aurora could be overhead or high in the sky. Maybe means it could show low on the horizon from a dark spot with a clear view towards the pole.
Every answer lists why: when it is dark enough, the highest Kp forecast while it is dark, the Kp your place needs, how bright the moon is, and a reminder that clouds are not checked.
The planetary K index comes from the NOAA Space Weather Prediction Center, measured for the past days and forecast for the next three, in 3 hour steps. A bar chart shows when activity peaks and the levels your place needs.
Where the aurora reaches follows NOAA's own rule of thumb: near 66 degrees magnetic latitude at Kp 0, about 2 degrees closer to the equator for each Kp level. The app works out your magnetic latitude from the World Magnetic Model 2025.
The app calculates when the sun is 12 degrees below the horizon at your place, so light summer nights in the far north are flagged as no go.
Save your town, a cabin or a trip destination and see tonight's answer for each in one list, in either hemisphere.
Turn on alerts for a Kp level, or let the app pick the level your place needs. Alerts come only for dark hours.
The last forecast is saved on the phone, and the app says how old it is. Forecasts are uncertain: treat the answer as a guide for whether to go out, not a promise.
Use it in your browser now, no account.
The phone app needs no signal.
What you enter stays on your device.
Contact
Aurora Window is in early access: the browser demo works today and the phone app follows when enough people ask for it. Tell us how you would use it and we will invite you first.
No newsletter and no selling of your details. Read how we handle messages in the contact privacy note.