December in Irun averages a daily high of 14.7°C with nights around 6.8°C. Expect roughly 15.2 wet days totalling 186.8mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Irun is May–October.
Based on SAN SEBASTIAN FUENTERRABIA, SP (2.4km), 1995–2024. 17 years of December data.