Dense Fog in Pennsylvania

Events

466

Deaths

0

Injuries

14

Damage

None recorded

• Dense Fog in Pennsylvania, October 9, 199812 injured · 2 eventsThe combination of deep easterly flow and Gulf moisture flowing northward and over a stalled frontal boundary produced a saturated environment across northeastern Pennsylvania on the 9th.
• Dense Fog and Freezing Fog in Pennsylvania, January 14 to 15, 201421 eventsA high pressure system over Pennsylvania combined with moist conditions at the surface from the rain earlier in the day on the 14th to produce widespread dense fog and even some black ice from the middle of the evening on the 14th through the morning on the 15th.
• Dense Fog and Winter Weather in Pennsylvania, December 19, 200420 eventsThe combination of a weak high pressure system over the region and low level moisture left in place by a departing low pressure system to the east caused dense fog to form across Eastern Pennsylvania after midnight EST on the 19th.
• Dense Fog in Pennsylvania, December 13 to 15, 200615 eventsThe combination of an unseasonably mild and moist air mass coupled with light overnight winds produced dense fog across southeastern Pennsylvania during the night of the 13th and the morning of the 14th.
• Dense Fog in Pennsylvania, January 12 to 13, 201313 eventsDense fog affected travel on both the mornings of the 12th and 13th in Eastern Pennsylvania. The most widespread and greatest impact on traveling occurred on the morning of the 13th. The fog was caused by a relatively moist and stagnant flow over the region on that weekend.
• Dense Fog in Pennsylvania, February 21, 201413 eventsThe combination of a relatively moist air mass, light winds preceding a warm front and snow cover produced widespread dense fog across Eastern Pennsylvania from the morning into the middle of the afternoon on the 21st.
• Dense Fog in Pennsylvania, December 31, 202213 eventsAn unusually long-lasting daylight dense fog event developed across most of eastern Pennsylvania on December 31st, 2022.
• Dense Fog in Pennsylvania, December 9 to 10, 202413 eventsWarm moist air advecting over a cold surface air mass resulted in widespread dense fog starting late on December 9th and continuing through much of the day December 10th.
• Dense Fog in Pennsylvania, May 15 to 16, 202513 eventsA moist low-level air mass north of an approaching warm front resulted in widespread dense fog across much of eastern Pennsylvania starting during the evening of May 15th and continuing into the early morning of May 16th. The fog dissipated after sunrise.
• Dense Fog in Pennsylvania, January 6 to 7, 202612 eventsA moist air mass north of a stalled warm front resulted in widespread dense fog late on January 6th and early on January 7th. The fog dissipated after sunrise.
• Dense Fog in Pennsylvania, February 21, 19961 injured · 3 eventsWidespread dense fog formed over northeast Pennsylvania during the early morning of the 21st, resulting in several accidents along Interstate 81 from Luzerne County northward to the New York State border. One person was injured in a four-car pileup in southern Susquehanna County.
• Dense Fog in Pennsylvania, January 5 to 6, 201411 eventsThe combination of snow on the ground, a moist southerly flow and a slowly northward moving warm front all helped produce dense fog across most of Eastern Pennsylvania from the evening of the 5th into the overnight.
• Dense Fog in Pennsylvania, January 26 to 27, 202411 eventsA stalled frontal boundary just south of the region resulted in stagnant, moist air across the area. Warm air lifted over the boundary facilitated the development of dense fog late on the 26th.
• Dense Fog in Pennsylvania, November 22 to 23, 199910 events
• Dense Fog in Pennsylvania, November 23 to 24, 199910 eventsA nearly stationary high pressure system anchored over the nearby Atlantic brought Eastern Pennsylvania dense fog for four days from the 21st through the 24th of November. Widespread visibilities of a quarter of a mile or less occurred.
• Dense Fog in Pennsylvania, November 20 to 21, 199910 events
• Dense Fog in Pennsylvania, November 21 to 22, 199910 events
• Dense Fog in Pennsylvania, February 22 to 23, 200310 eventsThe combination of heavy rain, humid air moving over the snow pack and relatively light winds produced widespread dense fog across Eastern Pennsylvania from the evening of the 22nd into the morning of the 23rd. Widespread visibilities were under one quarter of a mile.
• Dense Fog in Pennsylvania, October 5 to 6, 200710 eventsA high pressure system that remained over the Delmarva Peninsula for the third consecutive morning caused widespread dense fog to form across the region. Dense fog formed in all areas around midnight EDT on the 6th and took until around 10 a.m. EDT to dissipate.
• Dense Fog in Pennsylvania, February 5, 200810 eventsA moist and unseasonably mild southerly flow that preceded and accompanied the arrival of a warm front helped produce dense fog across all of eastern Pennsylvania on the morning of the 5th. Dense fog initially formed in the Poconos and spread southward during the predawn hours.
• Dense Fog in Pennsylvania, September 24, 202510 eventsA moist air mass near a stationary front resulted in areas of dense fog before dawn on September 24th. The fog dissipated shortly after sunrise.
• Dense Fog in Pennsylvania, January 24, 20249 eventsA slow moving warm front brought dense fog to eastern Pennsylvania during the midday and afternoon hours on January 24th. As the front continued to lift north, the fog slowly dissipated during the evening.
• Dense Fog in Pennsylvania, June 17, 20251 injured · 1 eventEasterly flow, allowing for an influx of low-level moisture from the Chesapeake Bay, allowed for fog development across portions of eastern Pennsylvania during the early morning hours of June 17, 2025.
• Dense Fog in Pennsylvania, December 2 to 3, 20238 eventsA stagnant and very moist air mass trapped between two stationary fronts resulted in a redevelopment of widespread dense fog late on December 2nd lasting into early on December 3.
• Dense Fog in Pennsylvania, December 2, 20238 eventsMoist stagnant air between two stationary fronts resulted in widespread dense fog starting before dawn on December 2nd and lasting into midday.

Dense Fog everywhereEvery kind of event in Pennsylvania

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24.