National Weather ServiceNew HampshireDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in New Hampshire
The National Weather Service issued 6 dense fog advisories for New Hampshire in 2025 and 10 a year on average in 2008-2025; in 2021-2025 it had the 45th most of any state. 2026 through September: 3, 58% below the average of 7 for those months in 2008-2025. Coastal Rockingham was covered most often (136 times since 2008).
How many dense fog advisories does New Hampshire get?
Every dense fog advisory that covered part of New Hampshire. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 3 |
| 2025 | 6 |
| 2024 | 7 |
| 2023 | 19 |
| 2022 | 10 |
| 2021 | 10 |
| 2020 | 13 |
| 2019 | 11 |
| 2018 | 17 |
| 2017 | 19 |
| 2016 | 7 |
| 2015 | 11 |
| 2014 | 12 |
| 2013 | 17 |
| 2012 | 9 |
| 2011 | 4 |
| 2010 | 0 |
| 2009 | 1 |
| 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 New Hampshire 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 New Hampshire?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Coastal Rockingham | 136 | 28 | June 28, 2026 |
| Strafford | 118 | 25 | June 28, 2026 |
| Interior Rockingham | 102 | 18 | June 28, 2026 |
| Eastern Hillsborough | 82 | 13 | June 28, 2026 |
| Merrimack | 68 | 13 | April 1, 2025 |
| Belknap | 67 | 12 | April 1, 2025 |
| Southern Carroll | 66 | 10 | April 1, 2025 |
| Western And Central Hillsborough | 65 | 8 | January 19, 2025 |
| Cheshire | 56 | 5 | December 29, 2024 |
| Northern Carroll | 49 | 5 | April 1, 2025 |
| Sullivan | 46 | 5 | December 29, 2024 |
| Southern Grafton | 44 | 5 | December 29, 2024 |
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 New Hampshire.