Cloud inversions happen when cold air sinks into the valleys overnight and fills them with mist, while warmer air sits above like a lid. We check each walk at its own highest point. Is there mist below the top at dawn? Is it clear just above the top? Is the air warmer up there than below? Plus light winds overnight and high pressure. A lower walk can be inside the mist on a morning when a higher one is above it, so they don't always agree.

The forecast describes the air in layers roughly 200 m apart, so the cloud top is always an estimate and we give it as a range. If a walk's high point is close to that range, it could go either way.

The northern lights need strong solar activity, clear skies and a dark night. Solar activity is the same everywhere, so the ranking comes down to which walk has the clearest sky at the best time. This far south we usually need about Kp 6 to see it by eye, and about Kp 5 for a phone camera pointed north.

It's a guide, not a promise. Always check the full mountain forecast before heading up in the dark.

Weather data by Open-Meteo.com (CC BY 4.0), using Met Office models. Space weather forecast from the NOAA Space Weather Prediction Center. For live UK aurora alerts, see AuroraWatch UK.