Methodology
Most tools hand you a Kp number and let you do the maths. We combine four independent things into one plain-language answer for your exact location — and we're honest about what the forecast can and can't tell you.
We read the live planetary Kp index from NOAA's Space Weather Prediction Center and translate it to your geomagnetic latitude — not your map latitude. The auroral oval is centred on the magnetic pole, so two cities at the same latitude can have very different odds. The result is a personal threshold: “visible here from Kp 5”.
Aurora is only visible once the sky is properly dark. We compute the sun's altitude for your exact spot, so a strong storm in daylight — or under the high-summer midnight sun — never produces a false “yes”. We also show tonight's dark window.
The most common reason people miss the aurora is simply cloud. We fold in current and hourly cloud cover from Open-Meteo for your coordinates, the way a weather-visibility forecast would — because a brilliant display is still invisible through an overcast sky.
A bright moon washes out faint aurora — but only when it is actually above the horizon. We check the moon's phase and altitude, so a full moon that has already set never counts against your verdict.
The four gates combine like a weakest-link chain, not an average. Clear skies and a high Kp are worthless if it isn't dark, or if a bright moon is up. So when conditions aren't ideal we name the single limiting factor — “Limited by daylight”, “Limited by heavy cloud”, “Limited by a bright moon” — instead of hiding it behind one number.
Space weather
— the planetary Kp index and 3-day / 27-day outlook from NOAA Space Weather Prediction Center.
Cloud cover
— current and hourly cloud from Open-Meteo.
Sun & moon
— darkness window and moon phase/altitude computed locally with the astronomical suncalc library.
Your location
— detected approximately from your IP for an instant answer, or precisely via your device on request.