Conditions on this page are calculated for . The live tool above re-runs the same model against the latest forecast for today's date.
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.
Weather decisions in Northern Lights Decision Guide are rarely about whether it's "nice" — they're about matching what you want to do with the conditions that actually show up. A perfectly sunny day at 34 °C can be a bad day for hiking, a mild overcast morning can be ideal for portrait photography, and a low-cloud evening can be a spectacular night for full-moon shots. Snap Weather is built to answer decision questions like these directly, rather than making you interpret raw forecast numbers on your own.
This page pulls the current Open-Meteo forecast for Northern Lights Decision Guide and reframes it around one specific decision. If the conditions clearly support the plan, we say so; if they don't, we say that too and — where possible — suggest the next date in the outlook window that does. Recommendations respect timezone, sunrise/sunset, forecast uncertainty and dealbreaker thresholds (heavy rain, dangerous wind, thick fog, hazardous UV), so a warning stays a warning even when everything else looks pleasant.
The decision score you see on this page is a weighted composite of the factors most important to the question in the page title. Weights differ by decision type, and every factor has a "dealbreaker" cap: if a single factor is dangerous or ruins the plan, the total score is pulled down regardless of the other factors.
Because dealbreaker caps apply, a "poor" score is not simply a low weather score — it means at least one factor makes the plan meaningfully worse or unsafe. That's the difference between a decision engine and a raw weather feed.
The table below summarises the typical weather pattern travellers can expect across the year in Northern Lights Decision Guide. It's a long-term climatological reference — the live tool at the top of this page overlays the current 7-to-14-day forecast on top of these baselines, so any anomalies (a cold spring, a wet summer, an unusual heatwave) show up immediately.
| Month | Season | Typical pattern | Traveller notes |
|---|---|---|---|
| January | Mid-winter (N) / peak-summer (S) | Coldest and shortest days in the northern hemisphere; warmest in the southern hemisphere. | Best value in most Europe/N-America; peak season in Australia/S-America/S-Africa. |
| February | Late-winter (N) / late-summer (S) | Cold and often driest month in the north; warm and stable in the south. | Ski season is at its most reliable in the northern hemisphere. |
| March | Early-spring (N) / early-autumn (S) | Rapidly lengthening days in the north; cooling but still pleasant in the south. | Shoulder pricing across most tourist cities. |
| April | Mid-spring (N) / mid-autumn (S) | Warming with unstable showers in the north; mild and dry in the south. | Cherry blossom windows across Europe, N America and East Asia. |
| May | Late-spring (N) / late-autumn (S) | Warm days, cool evenings in the north; first frosts possible in the south. | Widely considered the best value month for European city trips. |
| June | Early-summer (N) / early-winter (S) | Long days, warming quickly in the north; short days and cold in the south. | Solstice window; peak golden hour length in far-north cities. |
| July | Peak-summer (N) / mid-winter (S) | Warmest month across most of the northern hemisphere; ski season in the south. | Heatwave risk in southern Europe and inland US. |
| August | Late-summer (N) / late-winter (S) | Warm and often humid in the north; last month of ski season in the south. | Monsoon peak in South and Southeast Asia. |
| September | Early-autumn (N) / early-spring (S) | Cooling, drier and more stable in the north; warming in the south. | Widely rated the best month for Mediterranean travel. |
| October | Mid-autumn (N) / mid-spring (S) | Foliage peak in temperate north; blossom season starting in the south. | Photography prime time; long golden-hour windows. |
| November | Late-autumn (N) / late-spring (S) | First cold spells in the north; warming rapidly in the south. | Off-season pricing across most Europe/N America. |
| December | Early-winter (N) / early-summer (S) | Shortest days and often the wettest month in maritime climates; long warm days in the south. | Solstice window; ski openings across the northern hemisphere. |
Season labels use the northern-hemisphere calendar for consistency. If Northern Lights Decision Guide sits south of the equator, the live tool at the top of the page inverts these automatically using the location's coordinates.
Snap Weather pulls forecast data every hour from Open-Meteo and combines it with high-precision solar and lunar calculations done in Northern Lights Decision Guide's local timezone. We translate raw numbers into a direct answer to the question in the page title. Every score is capped so a single dealbreaker — heavy rain, dangerous wind, thick fog, hazardous UV — cannot be hidden by otherwise pleasant averages, and every recommendation includes a plain-English explanation of why we picked what we picked.
Uncertainty is stated rather than hidden. Every day carries a confidence band that falls with forecast lead time and with how variable the forecast itself is: days one to three are normally safe to plan around, days four to six describe a direction of travel, and anything beyond a week should shape intent rather than a booking. This confidence figure is a transparent, documented function of lead time and forecast variability — it is not a measurement of ensemble member spread, and we do not present it as one.
The methodology is documented in full on our methodology page, and the scoring code for each decision type — travel days, photography, weddings, activities, ski, running, cycling — is written in a shared, activity-aware library so recommendations stay consistent across every page on the site.
All times on this page render in the local timezone of Northern Lights Decision Guide, not your device timezone, so a sunrise time you read from London still means "sunrise as seen from Northern Lights Decision Guide". Weather data comes from Open-Meteo's hourly forecast API, which serves a blend of leading global models (ECMWF, GFS, ICON) at roughly 11 km resolution. Astronomical data — sunrise, sunset, twilight, moon phase, illumination and moon altitude — comes from the Sunrise-Sunset API with Open-Meteo as a resilient fallback, and every calculation is done in the target location's timezone rather than the browser's, so daylight-saving transitions, high-latitude twilight and equatorial no-twilight days all render correctly.
We publish a last-updated timestamp on the live page so you can see exactly how fresh the numbers are, and we display forecast confidence next to each day so you know when it's safe to lock in plans and when to check back after the next model run. The interactive tool at the top of this page is fully client-side — no accounts, no paywall, no email required — and it works on mobile and desktop equally well.
Weather data refreshes hourly from Open-Meteo. Solar and lunar timings are re-computed on every page load, so a page you refresh at midday and again at 6 pm can show meaningfully different scores if a model run has arrived in between.
Yes. Every forecast, decision score, month-by-month guide and photography timing on Snap Weather is free, no account required and no data captured beyond anonymous analytics. If it saves you a trip or a shoot, telling a friend is the only "payment" we ask for.
We use Open-Meteo's forecast API, which serves a blend of leading global models (ECMWF, GFS, ICON) at roughly 11 km resolution. This is the same model family used by many professional planning tools, exposed here in a decision-friendly way.
Yes — all sunrise, sunset, twilight and moon times are calculated in the destination's local timezone, so daylight-saving transitions are handled automatically. You should never need to add or subtract an hour manually.
Trust decays with time. Days 1–3 are typically very reliable, days 4–7 are directionally reliable (good/bad but not exact), and days 8–14 give you a broad sense of the pattern. That's why we surface confidence alongside every score.
Snap Weather is a weather decision engine. You can search any of the 11M+ locations in the Open-Meteo geocoding database, and we publish in-depth pages for 350+ curated destinations. If you're on the live site, the interactive forecast for Northern Lights Decision Guide loads automatically — no reload required.