Aurora forecasting guides: Kp, OVATION, darkness and cloud
Six guides on reading an aurora forecast: the Kp index, the OVATION map, geomagnetic latitude, seasonal darkness, forecast range and cloud cover.
Tämä sivu on kirjoitettu englanniksi.
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The Kp index explained: from quiet nights to G5 storms
What Kp measures, how NOAA turns it into G1 to G5 storm levels, and which Kp you need at Nordic, Icelandic, Canadian and Alaskan latitudes.
Päivitetty 17 October 2026
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How to read NOAA's OVATION aurora map
What the green oval on NOAA's aurora map models, why it looks 30 to 90 minutes ahead, what a percentage on it means and what it leaves out.
Päivitetty 17 October 2026
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Geomagnetic latitude: why Yellowknife can beat Rovaniemi
Aurora follows the magnetic field, not the map grid. Geomagnetic latitude for six destinations and the Kp at which the oval reaches each of them.
Päivitetty 17 October 2026
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Aurora season: how many hours are dark enough, month by month
Hours with the sun more than 12 degrees below the horizon on the 15th of every month at six aurora destinations, and why midsummer has none.
Päivitetty 17 October 2026
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How far ahead can an aurora forecast be trusted?
From the 30 to 90 minute OVATION nowcast to the 3-day Kp forecast and the 27-day outlook: what each NOAA product sees and when to check it.
Päivitetty 17 October 2026
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Cloud cover and aurora: how to judge a clear sky
What total cloud cover means in MET Norway forecasts, how percent maps to oktas, and how Aurorix decides that a sky is clear enough.
Päivitetty 17 October 2026