National Weather ServiceDense Fog AdvisoryVTEC FG.YArchive to October 1, 2026
Dense Fog Advisory: what it means and how often it is issued
The National Weather Service issued 1,882 dense fog advisories in 2025 and 1,470 a year on average in 2008-2025; Texas, California and Florida got the most in 2021-2025. 2026 through September: 1,183, 29% above the average of 920 for those months in 2008-2025.
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.
Source: National Weather Service directives and glossary.
How many dense fog advisories a year?
National count: each dense fog advisory counted once, whatever the number of states it covers. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 1,183 |
| 2025 | 1,882 |
| 2024 | 1,963 |
| 2023 | 1,740 |
| 2022 | 1,413 |
| 2021 | 1,602 |
| 2020 | 1,576 |
| 2019 | 1,711 |
| 2018 | 1,503 |
| 2017 | 1,603 |
| 2016 | 1,209 |
| 2015 | 1,417 |
| 2014 | 1,341 |
| 2013 | 1,305 |
| 2012 | 1,393 |
| 2011 | 1,188 |
| 2010 | 1,215 |
| 2009 | 1,234 |
| 2008 | 1,161 |
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?
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.
Which states get the most dense fog advisories?
Yearly average per state, 2021-2025. A dense fog advisory covering two states counts in both.
| State | A year, 2021-2025 | A year, 2008-2025 | 2025 |
|---|---|---|---|
| Texas | 196 | 183 | 220 |
| California | 146 | 107 | 188 |
| Florida | 141 | 120 | 176 |
| Kansas | 102 | 93 | 124 |
| Georgia | 99 | 88 | 101 |
| Mississippi | 94 | 76 | 113 |
| Minnesota | 93 | 72 | 84 |
| Alabama | 87 | 78 | 117 |
| Louisiana | 86 | 71 | 113 |
| Nebraska | 83 | 63 | 94 |
| Illinois | 76 | 69 | 93 |
| Missouri | 75 | 70 | 105 |
| Iowa | 75 | 65 | 76 |
| Wisconsin | 74 | 64 | 89 |
| Alaska | 70 | 60 | 76 |
| Oregon | 69 | 50 | 61 |
| North Carolina | 61 | 60 | 52 |
| Arkansas | 56 | 49 | 62 |
| Indiana | 53 | 45 | 61 |
| Tennessee | 53 | 42 | 65 |
| South Dakota | 51 | 34 | 48 |
| Washington | 51 | 33 | 52 |
| South Carolina | 45 | 54 | 29 |
| Oklahoma | 45 | 38 | 57 |
| Virginia | 39 | 36 | 28 |
| North Dakota | 39 | 33 | 30 |
| Kentucky | 38 | 35 | 47 |
| Maine | 38 | 28 | 28 |
| Ohio | 36 | 30 | 44 |
| Pennsylvania | 35 | 27 | 46 |
| Colorado | 34 | 34 | 43 |
| Montana | 34 | 29 | 34 |
| Wyoming | 28 | 21 | 32 |
| Michigan | 26 | 31 | 21 |
| Idaho | 25 | 23 | 21 |
| Maryland | 24 | 26 | 13 |
| West Virginia | 23 | 18 | 27 |
| New Mexico | 20 | 12 | 25 |
| New York | 17 | 20 | 12 |
| Massachusetts | 15 | 18 | 4 |
| New Jersey | 14 | 14 | 10 |
| Connecticut | 13 | 16 | 6 |
| Rhode Island | 11 | 13 | 2 |
| Utah | 11 | 11 | 8 |
| New Hampshire | 10 | 10 | 6 |
| Delaware | 9 | 8 | 5 |
| Arizona | 9 | 8 | 6 |
| District of Columbia | 3 | 5 | 0 |
| Vermont | 2 | 2 | 0 |
| Nevada | 1 | 2 | 0 |
| Hawaii | 0 | 0 | 0 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.