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About this tool
Estimate possible aurora visibility from the Kp index and your location.
The Aurora Visibility Forecast reads the latest planetary K-index from NOAA's Space Weather Prediction Center and compares your latitude against a simple visibility boundary of 67 degrees minus 2.2 times Kp — so at Kp 0 the screen sits near 67 degrees and at Kp 7 it drops to about 51.6 degrees. If your latitude is poleward of that line, conditions pass a first screening for possible aurora. It is a fast go / no-go check for aurora chasers and photographers deciding whether tonight is worth driving for, not a substitute for a full auroral oval forecast.
Open Aurora Visibility Forecast on AltFTool — it loads instantly in your browser.
Enter your latitude and longitude, or press Use device location to fill them from the browser.
Press Get current result to fetch the latest planetary K-index from NOAA's Space Weather Prediction Center.
Read the Latest UTC timestamp, the Kp value, your latitude and the simple latitude boundary to see whether you clear the screen.
The value comes from NOAA SWPC's planetary K-index feed each time you press for a reading, and the result shows the source timestamp in UTC so you can see how fresh it is.
You enter coordinates or use device location, and the screen compares your absolute latitude against the computed boundary, so a yes or no applies to where you actually are.
The result lists the Kp value, your latitude and the boundary figure side by side, so you can see how close a marginal call was instead of getting an unexplained verdict.
Rearrange the screen: you need a Kp of roughly (67 minus your latitude) divided by 2.2. At 55 degrees that is about Kp 5.5; at 60 degrees about Kp 3.2; at 50 degrees about Kp 7.7. Higher Kp pushes the auroral oval further towards the equator.
Kp is a planetary geomagnetic activity index on a 0 to 9 scale, derived from magnetometer readings at a network of ground observatories and published in three-hour intervals. NOAA's G-scale for geomagnetic storms starts at Kp 5 (G1) and reaches G5 at Kp 9.
No. This is a latitude-and-Kp screen only. Darkness, cloud cover, moonlight, light pollution, your local horizon to the north, and the difference between geographic and geomagnetic latitude all matter, and any one of them can rule out a night that clears the boundary.
It is fetched on demand when you request a result, and the row labelled Latest UTC shows the timestamp NOAA attached to that Kp value. Kp is reported in three-hour periods, so a value can be up to a few hours old even when the fetch is instant.