Alexander Westenberger and Ivana Siric have been crowned champions of the 2026 Istria 100 by UTMB, the Croatian ultramarathon that kicked off the European spring trail calendar over the weekend of 10–12 April. Run across the Istrian peninsula's karst uplands and coastal singletrack, the 100-mile race remains one of the most technically demanding fixtures on the UTMB World Series and continues to function as a crucial early-season proving ground for runners targeting UTMB Mont-Blanc later in the summer.
Westenberger's winning run broke open a slow-moving men's field in the final third of the race, pulling clear of home favourites Pavle Kruljac and Matija Mestric on the long descents into Motovun. The German-speaking Austrian finisher, a podium contender in the European series over the last two seasons, capped a patient performance with a final-quarter acceleration through the vineyards north of Buje. Kruljac and Mestric rounded out the men's podium in second and third, giving the host nation a significant domestic showing at its flagship ultramarathon.
The women's race was a Croatian showcase. Ivana Siric moved decisively to the front shortly after halfway and extended her margin through the final night to win by a comfortable cushion, with compatriot Maja Bonacic second and Czech runner Lenka Hiklova third. Siric's win is her most significant international result to date and slots her directly into conversations around the deeper-field races of the summer, including CCC and TDS at UTMB Mont-Blanc, for which she now holds a qualifying performance at the maximum UTMB Index multiplier.
Conditions were kinder than recent editions. After a saturated 2024 and a hot 2025, runners encountered cool overnight temperatures, a drying trail and a manageable breeze off the Adriatic. Course director reports noted fewer technical incidents at the notorious Buzet limestone sections, and finish rates across the 100-mile, 69-mile and 42-mile distances were up on both of the last two years. The accompanying 20K trail race around Umag also drew a record participant count, underlining Istria's continued consolidation as a spring destination for UK and Benelux trail runners who prefer travel over a flight to the Alps.
Istria 100 by UTMB sits at the beginning of a congested European trail spring. The Madeira Island Ultra Trail follows on 25 April, the Canyons Endurance Runs in California take place the same weekend, and Zegama-Aizkorri caps the month on 26 April. For runners building a UTMB Mont-Blanc campaign, the block between now and mid-June is critical for stones accumulation and recovery — and Westenberger and Siric both now face the familiar question of whether to double up or pivot to a shorter mountain race ahead of Chamonix in late August.