October in Longmont averages a daily high of 19°C with nights around 0.5°C. Expect roughly 4.8 wet days totalling 19.8mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Longmont is September–October.
Based on LONGMONT 2 ESE, CO US (2.1km), 1995–2024. 17 years of October data.