Marathon Eryri

This edition is listed as Marathon in Llanberis, Gwynedd, UK.

When we have race morning history, use that range for planning, not as a promise. Inside about 14 days, the live forecast on this page is the better read. We do not invent a start-hour number when history is not loaded here.

Inside about 14 days, use the live forecast on this page. The current outlook is about 6°C to 8°C, around 12 km/h wind and 86% humidity. Forecasts move. Further out, use race morning history, not a locked plan.

Heat, humidity, wind or a lumpier day than you hoped all raise the chance of a late fade. If the start feels easy, don't spend it. Back off early, and hold even effort even if that means slower than the A-goal. The preview on this page is the starting point. Full personalised splits sit in Race Pass or Pro.

About 719 m of climbing and 733 m of descent. Hilly. 48% sits within 2%. About 19% of the course is steeper than 6%. 5 climbs. One of those is steeper than 6%.

It is an estimate of how the course and conditions could move your baseline. Your body still decides the rest: heat adaptation, fuelling, prep, mindset, how you race, and whether you can draft.

The free page covers conditions, course context and a finish preview. Full personalised pacing and weather-adjusted splits sit in Race Pass or Pro.