Aurora Forecast

How Aurora Visibility Is Forecast

Seeing the aurora requires two things to align: geomagnetic activity strong enough to push the auroral oval over your location, and clear skies to see it through. Most aurora forecast tools only address the first half. Clear Skys combines both.

Geomagnetic activity is measured by the Kp index, a 0–9 scale indicating how disturbed Earth's magnetic field is. Higher Kp means the auroral oval expands further from the poles, making the aurora visible at lower latitudes. The NOAA 3-day Kp forecast gives a 3-hour resolution prediction covering the next three nights.

The second data source is the NOAA Ovation model, which provides a real-time probability map based on current solar wind measurements. Ovation is more granular than the Kp index — it tells you the actual probability of aurora overhead at your specific coordinates right now, not just a global activity level.

Clear Skys fetches both and combines them with local cloud cover. A Kp of 7 is worthless if your sky is overcast, and a clear sky doesn't help if Kp is 1 and you're in London. The forecast gives you the complete picture in one place.

What Kp Do You Need?

The Kp threshold for seeing the aurora depends entirely on your latitude. Locations within the auroral zone (65°N and above — Tromsø, Fairbanks, Reykjavik) can see aurora with Kp as low as 1 or 2. These are the most reliable places to see the northern lights, with displays on most clear nights during the aurora season.

At 60°N (southern Norway, central Scotland, southern Alaska), you need Kp 3 or above. At 55°N (northern England, southern Scandinavia, central Canada), Kp 5 is the threshold — a moderate geomagnetic storm. At 50°N (London, Paris, Vancouver), you need Kp 6 — a strong storm that happens maybe 10–15 times per year. At 45°N (Minneapolis, Milan, Montreal), Kp 7–8 is required — a severe storm, a few times per year at best. Below 40°N, only extreme events (Kp 9, the maximum) produce visible aurora, and these are rare.

Clear Skys applies these latitude thresholds automatically. Your forecast won't show "aurora possible" unless the predicted Kp meets the minimum for your location. When it does, the description scales with how far above threshold the Kp is: at threshold you might see a glow on the northern horizon; Kp +1 above threshold means good activity; Kp +2 above means potentially vivid, overhead displays.

Best Places to See the Northern Lights

The ideal aurora-watching location combines high latitude (65–70°N), frequent clear skies, and dark surroundings. The classic destinations sit within the auroral zone where activity is most frequent:

**Tromsø, Norway** (69.6°N) — the most popular aurora destination in Europe. Above the Arctic Circle, with a mild climate for its latitude thanks to the Gulf Stream. Aurora season runs roughly September to March.

**Reykjavik, Iceland** (64.1°N) — accessible and within the auroral zone, though Icelandic weather means cloud cover is a constant challenge. Driving outside the city to escape light pollution and find clear patches is standard practice.

**Fairbanks, Alaska** (64.8°N) — cold but frequently clear in winter, making it one of the most statistically reliable aurora locations. The interior climate produces less cloud than coastal alternatives.

**Kiruna, Sweden** (67.9°N) — a dark-sky haven in Swedish Lapland. Less touristy than Tromsø, with comparable aurora frequency.

**Anchorage, Alaska** (61.2°N) — slightly south of the optimal zone but still catches strong displays. More accessible than Fairbanks with better infrastructure.

Each of these has a dedicated forecast page on Clear Skys with aurora probability, Kp data, and local cloud conditions.

Aurora Forecasts by Location

Check aurora conditions at popular northern lights destinations: