Pittsburgh, Pa. – Drivers across western Pennsylvania may face dense fog and visibility under a half mile by 7 a.m. Monday, creating hazardous travel conditions for the morning commute.
According to the National Weather Service in Pittsburgh, the combination of light winds, clearing skies, and abundant surface moisture will lead to the development of radiation fog overnight. Areas most at risk include Pittsburgh, Butler, Indiana, and Johnstown, where the chance of visibility dropping below ½ mile exceeds 70%.
The highest probabilities—up to 75%—are centered near Pittsburgh and the I-79 corridor, with surrounding counties like Armstrong, Westmoreland, and Cambria also at elevated risk. The fog is expected to form between midnight and 4 a.m., lingering through the early daylight hours.
Motorists are urged to allow extra travel time, use low-beam headlights, and avoid sudden braking. Pedestrians and cyclists should wear reflective gear and use extra caution during early commutes.
Radiation fog typically forms after sunset under clear skies with light winds, when heat absorbed during the day is released into space, cooling near-surface air. This setup mirrors similar fog events seen in the region during late summer transitions.
Fog advisories may be issued overnight. Drivers should check weather.gov/pittsburgh for updates and plan accordingly for reduced visibility through early Monday.
