Conditions on this page are recalculated from the latest forecast every time it is opened, for the current date in the location's own time zone.
Visible across 60–70°N, faint visible to 55°. The "go" threshold for most aurora chasers. Once-a-year-or-rarer event — aurora to 40°N latitude, overhead corona on the oval. Broken cloud — hunt the gaps, drive 10–30 km if a hole sits over a north-facing horizon. Only substorms punch through. Aggressive chasing — check Windy/Yr every 15 minutes. Aurora invisible. Drive to a clear-sky region or accept the night is lost. Charged particles from the Sun (solar wind) collide with Earth's magnetic field. The field channels them toward the poles where they hit oxygen and nitrogen atoms in the upper atmosphere (90–300 km up), making them glow — green for oxygen at 100–250 km, red for oxygen at 300+ km, and violet/blue for nitrogen. Kp is a 0–9 planetary geomagnetic activity index measured every 3 hours. Higher Kp = stronger geomagnetic storm = the auroral oval shifts further south. Kp 4 = visible across most aurora-zone sites; Kp 6 (G2 storm) = visible to mid-latitudes like London; Kp 7+ is a once-a-year event reaching 40°N. A 0–100 score from a pure function with six inputs: Kp index (strongest signal), cloud cover (the absolute blocker), moon illumination, your latitude, light pollution and astronomical darkness hours. The score starts at 60 — aurora is a treat, not a default — and Kp can lift it above 90 while overcast skies can crash it below 20. No. Aurora requires three independent things to align: space weather (Kp), sky weather (clouds, moon), and earth-side conditions (darkness, latitude, light pollution). All three are needed. A perfect Kp 8 storm under overcast skies scores worse than a Kp 3 night under crystal-clear sky at Abisko. Reliably: 1–3 days for major storms (NOAA SWPC 3-day forecast, based on ACE/DSCOVR solar-wind monitors at L1). 27 days for active sunspot regions rotating back to Earth-facing. Long-term: 11-year solar cycle — 2024–2026 is peak activity, the best aurora years since 2014. Equinox months (March, September) statistically produce 30–40% more aurora than solstice months due to the Russell-McPherron effect. October–March covers all the dark-sky months. Avoid May–July inside the Arctic Circle — there's no astronomical darkness. Minimum 5 nights in any aurora location to outlast cloud cycles. 7+ nights for marginal-cloud locations (Lofoten, Vík, Reykjavík). 3 nights is a gamble even in Yellowknife or Abisko — pay extra to extend if forecast is poor. For statistical reliability: Yellowknife (Canada, 92/100), Abisko (Sweden, 90), Fairbanks (Alaska, 85). For scenery: Lofoten (Norway), Vík (Iceland), Ilulissat (Greenland). For comfort: Kakslauttanen glass igloos (Finland), Tromsø (Norway). Use the Plan My Aurora wizard above to match a site to your goal. A localised microclimate called the "Blue Hole of Abisko" — the surrounding mountains create a rain shadow that keeps the area dramatically clearer than the rest of Lapland. Combined with a 68°N latitude inside the auroral oval, near-zero light pollution and 16 hours of winter darkness, it's the most statistically reliable aurora site on Earth. Only during strong geomagnetic storms (Kp 6+, G2-class or higher) and only on the northern horizon. Roughly 5–10 nights per year on average, more during solar maximum. Sign up for NOAA alerts and be willing to drive 1–2 hours to a dark site on short notice. The auroral oval normally sits at 65–72° magnetic latitude. Move 5° south and you need a Kp one full point higher for the same visibility. From 50°N you need Kp 6+; from 40°N you need a once-in-a-decade Kp 8+ event. The Aurora Score penalises latitudes below 55° accordingly. No, but it reduces them. A full moon (95%+ illumination) washes out faint arcs — Kp ≤ 3 displays become invisible. But Kp 5+ storms remain spectacular under full moon and the moonlit foreground actually helps photography. Plan around the new-moon week if maximum colour matters; embrace the full moon if you want lit foregrounds. Under 30%: ideal — horizon-to-zenith visibility. 30–60%: workable, hunt the gaps. Over 70%: no point staying out unless you can drive to a clearer area. Cloud cover is the single most important "killer" — even a perfect Kp 7 storm is invisible under overcast. Drag the six sliders to match the now-cast Kp + sky forecast. The Aurora Score, archetype and breakdown update live.
Scores are capped by dealbreakers — heavy rain, dangerous wind, thick fog or hazardous UV pull a day down no matter how pleasant the rest of the numbers look. Forecast data is Open-Meteo; solar and lunar values are computed for Northern Lights Decision Guide's own coordinates and time zone. Full details on the methodology page.