National Weather ServiceDelawareDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in Delaware
The National Weather Service issued 5 dense fog advisories for Delaware in 2025 and 8 a year on average in 2008-2025; in 2021-2025 it had the 46th most of any state. 2026 through September: 10, 98% above the average of 5 for those months in 2008-2025. New Castle was covered most often (122 times since 2008).
How many dense fog advisories does Delaware get?
Every dense fog advisory that covered part of Delaware. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 10 |
| 2025 | 5 |
| 2024 | 11 |
| 2023 | 11 |
| 2022 | 14 |
| 2021 | 4 |
| 2020 | 13 |
| 2019 | 7 |
| 2018 | 13 |
| 2017 | 6 |
| 2016 | 2 |
| 2015 | 15 |
| 2014 | 8 |
| 2013 | 6 |
| 2012 | 15 |
| 2011 | 4 |
| 2010 | 4 |
| 2009 | 5 |
| 2008 | 3 |
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 Delaware 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 Delaware?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| New Castle | 122 | 27 | April 3, 2026 |
| Delaware Beaches | 109 | 23 | April 3, 2026 |
| Kent | 104 | 21 | April 3, 2026 |
| Inland Sussex | 101 | 20 | April 3, 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 Delaware.