Dense Fog — Northwestern San Juan Mountains, Colorado

2025-11-20 · Northwestern San Juan Mountains, Colorado

Event narrative

Areas of dense fog developed within high-elevation valleys of the San Juan mountains resulting from multiple hours of snowfall during the early overnight period. The KTEX AWOS at the Telluride Regional Airport reported about four hours of 1/4-mile visibility from freezing fog around sunrise on the 20th. No reports of injuries, damages, or fatalities were received.

Wider weather episode

Southwesterly flow ahead of a trough brought increased moisture to southwestern Colorado. Terrain-driven showers fell over portions of the San Juan mountains as a result. Falling overnight temperatures paired with the increased moisture promoted widespread dense fog over high-elevation valleys in the San Juans.

Source: NOAA Storm Events Database, event_id 1300391. Narrative written by the NWS forecast office that issued the report.