Dense Fog Advisories in Illinois, 2020

Dense Fog Advisories by county

Each county as a circle sized by its count in 2020. Tap one for its archive.

Over time

By month

The alerts

Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.

Issued	Product	Office	Counties	Lasted
Jan 3, 1:12 AM CST	Dense Fog Advisory	ILX	Champaign, Christian, Clark, Coles, Cumberland, Douglas and 7 more	8 hr
Jan 3, 4:15 AM CST	Dense Fog Advisory	LSX	Bond, Clinton, Fayette, Madison, Marion, Monroe and 4 more	5 hr
Jan 14, 9:19 AM CST	Dense Fog Advisory	PAH	Alexander, Hardin, Massac, Pope, Pulaski	3 hr
Jan 14, 7:53 PM CST	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 23 more	13 hr
Jan 14, 8:20 PM CST	Dense Fog Advisory	LSX	Bond, Fayette, Macoupin, Montgomery	7 hr
Jan 14, 8:49 PM CST	Dense Fog Advisory	LOT	Ford, Iroquois, Kankakee, Livingston	14 hr
Jan 14, 9:27 PM CST	Dense Fog Advisory	PAH	Alexander, Johnson, Massac, Pulaski, Union	4 hr
Jan 24, 6:21 AM CST	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Coles, DeWitt, Douglas and 21 more	9 hr
Jan 24, 8:29 AM CST	Dense Fog Advisory	DVN	Bureau, Hancock, Henderson, Henry, McDonough, Mercer and 2 more	7 hr
Jan 24, 8:34 AM CST	Dense Fog Advisory	LOT	Boone, DeKalb, DuPage, Ford, Grundy, Iroquois and 8 more	11 hr
Jan 26, 3:40 AM CST	Dense Fog Advisory	DVN	Hancock, Henderson, McDonough, Warren	6 hr
Jan 26, 3:00 PM CST	Dense Fog Advisory	DVN	Hancock	19 hr
Jan 26, 3:09 PM CST	Dense Fog Advisory	LSX	Adams, Brown, Calhoun, Greene, Jersey, Macoupin and 4 more	21 hr
Feb 1, 12:49 AM CST	Dense Fog Advisory	DVN	Rock Island	6 hr
Feb 17, 5:27 PM CST	Dense Fog Advisory	DVN	Bureau, Carroll, Hancock, Henderson, Henry, McDonough and 5 more	7 hr
Feb 17, 5:44 PM CST	Dense Fog Advisory	ILX	Cass, Champaign, DeWitt, Fulton, Knox, Logan and 14 more	8 hr
Feb 17, 6:10 PM CST	Dense Fog Advisory	LSX	Adams, Brown, Calhoun, Greene, Jersey, Macoupin and 1 more	7 hr
Feb 17, 8:24 PM CST	Dense Fog Advisory	LOT	Boone, DeKalb, DuPage, Ford, Grundy, Iroquois and 10 more	6 hr
Mar 12, 2:39 AM CDT	Dense Fog Advisory	PAH	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more	7 hr
Mar 12, 6:05 AM CDT	Dense Fog Advisory	LSX	Adams, Bond, Brown, Calhoun, Clinton, Fayette and 11 more	4 hr
Mar 12, 6:39 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 29 more	5 hr
Mar 12, 8:42 AM CDT	Dense Fog Advisory	LOT	Ford, LaSalle, Lee, Livingston, Ogle	2 hr
Mar 12, 10:04 AM CDT	Dense Fog Advisory	LSX	Adams, Bond, Brown, Calhoun, Clinton, Fayette and 11 more	116 min
Mar 18, 11:10 PM CDT	Dense Fog Advisory	PAH	Alexander, Johnson, Massac, Pope, Pulaski, Union	8 hr
Mar 19, 6:41 AM CDT	Dense Fog Advisory	LOT	Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more	3 hr
Mar 19, 10:07 AM CDT	Dense Fog Advisory	LOT	Lake	113 min
Mar 23, 5:21 AM CDT	Dense Fog Advisory	LOT	Boone, DeKalb, Kane, Lake, McHenry, Ogle and 1 more	5 hr
Mar 25, 1:51 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 29 more	9 hr
Mar 25, 3:31 AM CDT	Dense Fog Advisory	LSX	Adams, Bond, Brown, Clinton, Fayette, Greene and 5 more	8 hr
Mar 25, 3:32 AM CDT	Dense Fog Advisory	PAH	Franklin, Hamilton, Jefferson, Johnson, Perry, Pope and 3 more	5 hr
Mar 25, 4:39 AM CDT	Dense Fog Advisory	LOT	Cook, DeKalb, Ford, Grundy, Iroquois, Kankakee and 7 more	6 hr
Mar 25, 4:41 AM CDT	Dense Fog Advisory	DVN	Bureau, Carroll, Hancock, Henderson, Henry, Jo Daviess and 7 more	5 hr
Mar 25, 11:02 AM CDT	Dense Fog Advisory	ILX	Clark, Clay, Crawford, Cumberland, Effingham, Jasper and 3 more	58 min
Apr 1, 10:43 PM CDT	Dense Fog Advisory	LOT	Cook, Will	10 hr
Apr 6, 6:20 AM CDT	Dense Fog Advisory	PAH	Edwards, Franklin, Gallatin, Hamilton, Jackson, Jefferson and 6 more	3 hr
Apr 8, 4:16 AM CDT	Dense Fog Advisory	LOT	Boone, DeKalb, Lee, McHenry, Ogle, Winnebago	5 hr
Apr 8, 4:22 AM CDT	Dense Fog Advisory	DVN	Carroll, Henry, Jo Daviess, Rock Island, Stephenson, Whiteside	5 hr
Apr 24, 2:13 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 29 more	7 hr
Apr 24, 3:00 AM CDT	Dense Fog Advisory	PAH	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more	6 hr
Apr 24, 3:06 AM CDT	Dense Fog Advisory	LSX	Bond, Clinton, Fayette, Macoupin, Madison, Marion and 5 more	6 hr
May 15, 3:00 AM CDT	Dense Fog Advisory	DVN	Jo Daviess	4 hr
May 24, 1:57 AM CDT	Dense Fog Advisory	DVN	Jo Daviess	6 hr
Jul 2, 5:05 AM CDT	Dense Fog Advisory	PAH	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more	3 hr
Jul 2, 5:57 AM CDT	Dense Fog Advisory	LSX	Bond, Clinton, Fayette, Greene, Jersey, Macoupin and 7 more	3 hr
Aug 22, 3:25 AM CDT	Dense Fog Advisory	PAH	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more	6 hr
Aug 23, 4:08 AM CDT	Dense Fog Advisory	PAH	Alexander, Franklin, Gallatin, Hamilton, Hardin, Johnson and 7 more	5 hr
Aug 26, 3:04 AM CDT	Dense Fog Advisory	ILX	Clark, Clay, Crawford, Cumberland, Edgar, Effingham and 3 more	5 hr
Sep 1, 4:35 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 19 more	4 hr
Sep 3, 2:58 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 19 more	6 hr
Sep 3, 3:15 AM CDT	Dense Fog Advisory	LSX	Bond, Calhoun, Clinton, Fayette, Greene, Jersey and 8 more	6 hr
Sep 9, 6:41 AM CDT	Dense Fog Advisory	ILX	Champaign, Christian, Coles, Cumberland, Douglas, Effingham and 8 more	4 hr
Sep 10, 7:12 AM CDT	Dense Fog Advisory	ILX	Clark, Clay, Coles, Crawford, Cumberland, Edgar and 3 more	108 min
Sep 12, 6:41 AM CDT	Dense Fog Advisory	PAH	Alexander, Jackson, Johnson, Massac, Perry, Pulaski and 1 more	2 hr
Sep 13, 4:51 AM CDT	Dense Fog Advisory	PAH	Alexander, Hardin, Massac, Pope, Pulaski	2 hr
Sep 26, 2:18 AM CDT	Dense Fog Advisory	PAH	Wabash	4 hr
Oct 11, 6:33 AM CDT	Dense Fog Advisory	ILX	Christian, Clark, Clay, Coles, Crawford, Cumberland and 6 more	3 hr
Oct 12, 6:00 AM CDT	Dense Fog Advisory	PAH	Edwards, Gallatin, Hardin, Massac, Pope, Saline and 2 more	2 hr
Oct 12, 6:35 AM CDT	Dense Fog Advisory	ILX	Clark, Crawford, Lawrence	2 hr
Oct 21, 1:43 AM CDT	Dense Fog Advisory	PAH	Alexander	7 hr
Oct 21, 9:34 PM CDT	Dense Fog Advisory	LSX	Adams, Bond, Brown, Calhoun, Fayette, Greene and 5 more	10 hr
Oct 22, 12:58 AM CDT	Dense Fog Advisory	ILX	Cass, Champaign, Christian, Clark, Clay, Coles and 26 more	6 hr
Oct 22, 2:35 AM CDT	Dense Fog Advisory	DVN	Bureau, Hancock, Henderson, Henry, McDonough, Mercer and 3 more	9 hr
Oct 22, 3:30 AM CDT	Dense Fog Advisory	LOT	Ford, Grundy, Iroquois, Kankakee, LaSalle, Livingston and 1 more	9 hr
Oct 22, 3:34 PM CDT	Dense Fog Advisory	DVN	Jo Daviess, Stephenson	11 min
Oct 22, 3:45 PM CDT	Dense Fog Advisory	DVN	Jo Daviess, Stephenson	6 hr
Nov 24, 9:16 PM CST	Dense Fog Advisory	DVN	Jo Daviess, Stephenson	11 hr
Dec 4, 8:21 AM CST	Dense Fog Advisory	PAH	Alexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	86 min

By county

Every county with at least one alert. A county page lists each alert that covered it.

62 more counties

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record The radar archive 2019 2021

Sources

National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.