Ultra-Trail Snowdonia by UTMB returns to Llanberis on Friday morning for a three-day takeover of Eryri, with the 164-kilometre miler leading off at first light on 15 May and racing rolling through to the final 25K finishers on Sunday afternoon. Race organisers confirmed this week that the UTS 100M, the UTS 80K and the UTS 100K are all sold out, with only the 53-kilometre UTS 50K still carrying late entries. Last year's event drew more than 2,800 runners from over 60 nationalities, and the 2026 weekend looks set to clear that figure comfortably given the speed at which the longer races filled.
The miler again carries the steepest billing. The 164-kilometre route loops out from Llanberis over the full ridge between Snowdon and the Glyderau, drops into the Ogwen valley, climbs the Carneddau, and returns south via the Moelwynion and Cnicht for a total of more than 10,000 metres of vertical gain. UTMB's index points multipliers and the race's reputation for foul weather have made it one of the most coveted European 100-milers on the World Series calendar, and the 36-hour cut-off is the unforgiving end of a course profile that rewards conservative early pacing.
Saturday's 100K stands out as the headline daytime race. The point-to-point course shares the ridge sections used by the miler but compresses them into a 17-hour cut-off, and the entry list this year includes a deep international field of UTMB World Series podium contenders. The 80K, also starting on Friday, has been redrawn to add an extra Glyderau crossing after feedback from 2025, while the 50K is being run as a single-loop event out of Llanberis to ease the strain on the village's narrow approach roads.
The forecast is the variable nobody controls. Eryri sat under a settled high-pressure system through early May, but a low pushing in from the Irish Sea is expected to deliver showers and gusts above the cloud line through Friday night and into Saturday morning. Race director briefings have already flagged the Crib Goch traverse and the descent off Glyder Fawr as the technical pinch-points where weather could force route adjustments, and runners have been reminded that the mandatory kit list will be checked at multiple intermediate stations rather than only at the start.
Live tracking opens on the UTMB Live platform from Friday morning, with race-by-race splits and a dot-watcher feed for every distance. The weekend slots neatly between Ultra-Trail Australia, which is already under way in Katoomba, and Sunday's Zegama-Aizkorri Marathon in the Basque Country, giving trail fans three continents of UTMB World Series racing to follow in a single window. Running Lookout will run rolling coverage from Llanberis through the weekend, with miler results expected late Saturday night into Sunday morning.