National Weather ServiceMontanaDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in Montana
The National Weather Service issued 34 dense fog advisories for Montana in 2025 and 29 a year on average in 2008-2025; in 2021-2025 it had the 32nd most of any state. 2026 through September: 13, 25% below the average of 17 for those months in 2008-2025. Western Roosevelt was covered most often (152 times since 2008).
How many dense fog advisories does Montana get?
Every dense fog advisory that covered part of Montana. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 13 |
| 2025 | 34 |
| 2024 | 43 |
| 2023 | 55 |
| 2022 | 18 |
| 2021 | 20 |
| 2020 | 17 |
| 2019 | 38 |
| 2018 | 35 |
| 2017 | 24 |
| 2016 | 17 |
| 2015 | 14 |
| 2014 | 17 |
| 2013 | 17 |
| 2012 | 30 |
| 2011 | 24 |
| 2010 | 66 |
| 2009 | 31 |
| 2008 | 15 |
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 Montana 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 Montana?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Western Roosevelt | 152 | 39 | September 24, 2026 |
| Central and Southern Valley | 148 | 34 | July 16, 2026 |
| Sheridan | 141 | 34 | September 24, 2026 |
| Eastern Roosevelt | 136 | 36 | September 24, 2026 |
| Daniels | 130 | 28 | September 24, 2026 |
| Northern Valley | 127 | 29 | July 16, 2026 |
| Richland | 107 | 26 | September 24, 2026 |
| Central and Southeast Phillips | 101 | 28 | July 16, 2026 |
| Missoula/Bitterroot Valleys | 98 | 17 | March 18, 2026 |
| Northern Phillips | 94 | 23 | July 16, 2026 |
| Dawson | 93 | 23 | September 24, 2026 |
| McCone | 85 | 16 | February 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 Montana.