Dense Fog Advisories in Illinois
1,407 dense fog advisories since 1986. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of dense fog advisories reaches back to 2005.
Dense Fog Advisories by county
Each county as a circle sized by its count since 1986. Tap one for its archive.
- Dense Fog Advisories
- 1,407
- Busiest year
- 201793 dense fog advisories
- Average year
- 64over 22 years on file
Over time
By year
Before late 2005 the archive holds only tornado, severe thunderstorm, flash flood and marine warnings, and from 1997 SPC's watches, so the jump that year is the archive widening, not the weather.
By month of the year
By county
Every county with at least one alert. A county page lists each alert that covered it.
- DeKalb County244
- Kane County233
- Lee County230
- McHenry County227
- Ogle County226
- Boone County224
- Winnebago County216
- Rock Island County206
- LaSalle County205
- Jo Daviess County203
- McLean County203
- Grundy County200
- Carroll County199
- Henry County199
- Kendall County199
- Lake County199
- DeWitt County198
- Champaign County197
- Piatt County197
- Whiteside County196
- Stephenson County195
- Coles County194
- Vermilion County193
- Mercer County191
- Clark County189
- Macon County189
- Cumberland County188
- Edgar County188
- Logan County187
- Shelby County186
- Livingston County185
- Moultrie County184
- Bureau County183
- Henderson County183
- Tazewell County183
- Douglas County182
- Woodford County182
- Putnam County181
- Kankakee County180
- Sangamon County180
62 more counties
- Warren County180
- Effingham County178
- Christian County177
- DuPage County177
- Jasper County176
- Mason County172
- Menard County172
- Ford County171
- Fulton County171
- Hancock County171
- McDonough County171
- Peoria County171
- Richland County170
- Clay County169
- Crawford County168
- Iroquois County168
- Cass County166
- Lawrence County165
- Morgan County165
- Knox County164
- Marshall County161
- Scott County161
- Stark County159
- Schuyler County156
- Alexander County140
- Pulaski County138
- Williamson County138
- Saline County136
- Union County136
- Hamilton County135
- Franklin County134
- Massac County133
- Pope County133
- Gallatin County132
- Johnson County132
- Jefferson County131
- Jackson County130
- White County128
- Adams County126
- Wayne County125
- Hardin County124
- Edwards County123
- Wabash County123
- Perry County122
- Pike County122
- Brown County119
- Bond County119
- Montgomery County119
- Saint Clair County118
- Macoupin County117
- Clinton County115
- Fayette County114
- Madison County114
- Marion County113
- Washington County111
- Monroe County109
- Jersey County104
- Randolph County103
- Greene County103
- Calhoun County97
- Will County68
- Cook County59
The latest dense fog advisories
The most recent on file, newest first.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 11, 2:07 AM CDT | Dense Fog Advisory | DVN | Hancock, Henderson, Henry, McDonough, Mercer, Rock Island and 1 more | 8 hr |
| Sep 10, 9:58 PM CDT | Dense Fog Advisory | ILX | Cass, Fulton, Knox, Mason, Menard, Morgan and 3 more | 11 hr |
| Sep 10, 9:56 PM CDT | Dense Fog Advisory | LSX | Adams, Brown, Pike | 12 hr |
| Sep 10, 4:12 AM CDT | Dense Fog Advisory | DVN | Bureau, Carroll, Putnam, Whiteside | 4 hr |
| Sep 10, 3:11 AM CDT | Dense Fog Advisory | LOT | Boone, DeKalb, DuPage, Kane, Kendall, LaSalle and 5 more | 5 hr |
| Aug 16, 4:31 AM CDT | Dense Fog Advisory | DVN | Rock Island, Whiteside | 4 hr |
| Aug 13, 2:42 AM CDT | Dense Fog Advisory | LOT | Boone, Cook, DeKalb, DuPage, Ford, Grundy and 10 more | 6 hr |
| Aug 13, 2:35 AM CDT | Dense Fog Advisory | DVN | Bureau, Carroll, Hancock, Henderson, Henry, Jo Daviess and 7 more | 6 hr |
| Aug 13, 2:29 AM CDT | Dense Fog Advisory | ILX | Champaign, DeWitt, Douglas, Edgar, Fulton, Knox and 11 more | 7 hr |
| Aug 7, 2:48 AM CDT | Dense Fog Advisory | ILX | Champaign, Christian, Clark, Coles, Cumberland, DeWitt and 8 more | 5 hr |
| Aug 7, 2:46 AM CDT | Dense Fog Advisory | LOT | Cook, Ford, Grundy, Iroquois, Kankakee, Livingston and 1 more | 6 hr |
| Jul 27, 3:39 AM CDT | Dense Fog Advisory | DVN | Bureau, Carroll, Henry, Jo Daviess, Putnam, Stephenson and 1 more | 4 hr |
Nearby
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.