Dense Fog — San Juan River Basin, Colorado

2025-12-07 · San Juan River Basin, Colorado

Event narrative

Localized dense fog developed in the San Juan River Basin during the morning of December 7. The KPSO AWOS at the Stevens-Pagosa Springs Airfield reported about thirty minutes of freezing fog reducing visibility to 1/4 mile shortly after sunrise. No reports of injuries, damages, or fatalities were received.

Wider weather episode

A strong plume of atmospheric river moisture arrived on the morning of December 6 from the northwest, bringing rain and snow showers to portions of the Colorado west slope. Overnight, the moisture plume descended southwards, leaving west-central and southwestern Colorado valleys to saturate. Dense fog was able to develop before and near sunrise in these valleys as a result, though poor radiational cooling from cloudy skies kept fog relatively localized and short-lived.

Source: NOAA Storm Events Database, event_id 1302442. Narrative written by the NWS forecast office that issued the report.