Dense Fog in Illinois, January 31, 2009

Name: Dense Fog in Illinois, January 31, 2009
Start: 2009-01-31T02:00
End: 2009-01-31T09:00
Location: Illinois

January 31, 2009 · NWS PAH · 10 events in 10 counties and zones

Widespread dense fog developed across far southern Illinois, mainly along and south of a line from Carbondale to Harrisburg. Visibility was below one-quarter mile.

Where it happened

Every event with a place to put it; 10 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 10

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PAH wrote it up.

Widespread dense fog developed across far southern Illinois, mainly along and south of a line from Carbondale to Harrisburg. Visibility was below one-quarter mile. Since temperatures were below freezing, light icing occurred in the thick fog. A light south wind flow of milder air over the snow and ice-covered ground set the stage for dense fog.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Paducah, KY wrote its last area forecast discussion before the first event at Jan 31, 12:20 AM CST, 1 hour 40 minutes earlier.

Area forecast discussion, Jan 31, 12:20 AM CST, 1 hour 40 minutes before

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In the hours before

Special weather statement, Jan 30, 8:07 PM CST, 5 hours 53 minutes before

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Local storm report, Jan 30, 8:31 PM CST, 5 hours 29 minutes before

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The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

10 dense fog. Local standard time, as filed.

Dense Fog, Alexander

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Alexander forecast zone
Reported by: AWOS
Coordinates: 37.192, -89.338 (the zone’s center; the record gives no point)

Dense Fog, Jackson

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Jackson forecast zone
Reported by: ASOS
Coordinates: 37.785, -89.382 (the zone’s center; the record gives no point)

Dense Fog, Johnson

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Johnson forecast zone
Reported by: ASOS
Coordinates: 37.460, -88.881 (the zone’s center; the record gives no point)

Dense Fog, Massac

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Massac forecast zone
Reported by: AWOS
Coordinates: 37.219, -88.708 (the zone’s center; the record gives no point)

Dense Fog, Pulaski

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Pulaski forecast zone
Reported by: AWOS
Coordinates: 37.223, -89.127 (the zone’s center; the record gives no point)

Dense Fog, Union

When: January 31, 2:00 AM CST to 9:00 AM CST
Where: Union forecast zone
Reported by: AWOS
Coordinates: 37.471, -89.255 (the zone’s center; the record gives no point)

Dense Fog, Hardin

When: January 31, 3:00 AM CST to 9:00 AM CST
Where: Hardin forecast zone
Reported by: AWOS
Coordinates: 37.518, -88.267 (the zone’s center; the record gives no point)

Dense Fog, Pope

When: January 31, 3:00 AM CST to 9:00 AM CST
Where: Pope forecast zone
Reported by: AWOS
Coordinates: 37.413, -88.562 (the zone’s center; the record gives no point)

Dense Fog, Saline

When: January 31, 3:00 AM CST to 9:00 AM CST
Where: Saline forecast zone
Reported by: AWOS
Coordinates: 37.753, -88.541 (the zone’s center; the record gives no point)

Dense Fog, Williamson

When: January 31, 3:00 AM CST to 9:00 AM CST
Where: Williamson forecast zone
Reported by: AWOS
Coordinates: 37.730, -88.930 (the zone’s center; the record gives no point)

What these are

Dense Fog: Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Illinois in 2009 Every state in 2009 This day in weather history Warnings in Illinois, January 2009

Sources

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 2026-10-01. Each event’s entry at NCEI: 149082, 149084, 149085, 149086, 149088, 149090, 149083, 149087, 149089, 149091.