National Weather ServiceIowaDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in Iowa
The National Weather Service issued 76 dense fog advisories for Iowa in 2025 and 65 a year on average in 2008-2025; in 2021-2025 it had the 13th most of any state. 2026 through September: 53, 19% above the average of 45 for those months in 2008-2025. Jones was covered most often (198 times since 2008).
How many dense fog advisories does Iowa get?
Every dense fog advisory that covered part of Iowa. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 53 |
| 2025 | 76 |
| 2024 | 110 |
| 2023 | 86 |
| 2022 | 39 |
| 2021 | 65 |
| 2020 | 70 |
| 2019 | 63 |
| 2018 | 76 |
| 2017 | 79 |
| 2016 | 74 |
| 2015 | 39 |
| 2014 | 53 |
| 2013 | 53 |
| 2012 | 70 |
| 2011 | 39 |
| 2010 | 79 |
| 2009 | 42 |
| 2008 | 65 |
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 Iowa 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 Iowa?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Jones | 198 | 44 | September 11, 2026 |
| Dubuque | 194 | 42 | September 11, 2026 |
| Jackson | 194 | 44 | September 11, 2026 |
| Osceola | 194 | 63 | September 30, 2026 |
| Clarke | 193 | 45 | September 17, 2026 |
| Cedar | 192 | 45 | September 11, 2026 |
| Clinton | 192 | 45 | September 11, 2026 |
| Lucas | 190 | 46 | September 17, 2026 |
| Marion | 190 | 49 | September 17, 2026 |
| Muscatine | 190 | 42 | September 11, 2026 |
| Scott | 190 | 42 | September 11, 2026 |
| Jasper | 189 | 45 | September 17, 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 Iowa.