Aurora Forecast & Spot Optimizer: 5 things matter, not just KP

Iceland is one of the world's best aurora-viewing destinations because it's directly under the auroral oval in winter (Sept–Mar). Most nights have some aurora activity overhead. The reason people come back saying "we didn't see the lights" is almost never that the aurora wasn't there — it's that it was cloudy, too dim to see through the city lights, or drowned out by a full moon.

The 5 factors that actually matter, ranked by importance: (1) cloud cover (40% of score), (2) moon phase (20%), (3) KP index (20%), (4) light pollution (15%), (5) patience / viewing window (5%). The KP index gets the most attention online but is the least variable factor in Iceland — KP 2–4 covers most nights.

Score is from 0–100. Below 30 = don't bother. 30–50 = worth checking. Above 70 = book a guide or drive out of the city. 80+ = you should be outside, right now, looking up.

The factors panel shows you which input is helping or hurting. The advice box gives a specific plan for the night: drive 30 min out, set up at viewpoint X, look north-east after 22:00, etc.

The forecast KP index is a 1–3 hour prediction, not a guarantee. Sudden solar events (CMEs) can spike it unexpectedly. The cloud cover forecast is also imperfect, especially in Iceland's microclimates — one valley can be clear while the next has full cloud. Always check the actual sky, not just the forecast.

This tool does not account for short-term solar wind data (Bz, density). For real-time, use the NOAA SWPC site and auroraforecast.com.