National Weather ServiceOhioDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in Ohio
The National Weather Service issued 44 dense fog advisories for Ohio in 2025 and 30 a year on average in 2008-2025; in 2021-2025 it had the 29th most of any state. 2026 through September: 36, 74% above the average of 21 for those months in 2008-2025. Williams was covered most often (125 times since 2008).
How many dense fog advisories does Ohio get?
Every dense fog advisory that covered part of Ohio. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 36 |
| 2025 | 44 |
| 2024 | 43 |
| 2023 | 37 |
| 2022 | 28 |
| 2021 | 30 |
| 2020 | 21 |
| 2019 | 32 |
| 2018 | 34 |
| 2017 | 43 |
| 2016 | 21 |
| 2015 | 32 |
| 2014 | 25 |
| 2013 | 21 |
| 2012 | 28 |
| 2011 | 28 |
| 2010 | 23 |
| 2009 | 21 |
| 2008 | 24 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
When in the year does Ohio get them?
Sum of 2008-2025; the busiest month is labelled.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
Where in Ohio?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Williams | 125 | 35 | August 7, 2026 |
| Defiance | 121 | 34 | August 7, 2026 |
| Clark | 120 | 26 | September 13, 2026 |
| Fulton | 120 | 36 | August 7, 2026 |
| Champaign | 119 | 26 | September 13, 2026 |
| Clinton | 117 | 24 | September 13, 2026 |
| Greene | 117 | 26 | September 13, 2026 |
| Darke | 116 | 27 | September 13, 2026 |
| Logan | 116 | 27 | September 13, 2026 |
| Henry | 115 | 34 | August 7, 2026 |
| Madison | 115 | 24 | September 13, 2026 |
| Shelby | 114 | 26 | September 13, 2026 |
The NWS issues these products for counties or forecast zones; a zone can be part of a county or a mountain range.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
What is a dense fog advisory?
A dense fog advisory means fog will cut visibility to a quarter mile or less over a wide area. An advisory is issued for a hazard less serious than a warning that can still cause inconvenience or danger if people are not careful. The national record · Every warning type in Ohio.