National Weather ServiceOregonDense Fog AdvisoryArchive to October 1, 2026
Dense Fog Advisories in Oregon
The National Weather Service issued 61 dense fog advisories for Oregon in 2025 and 50 a year on average in 2008-2025; in 2021-2025 it had the 16th most of any state. 2026 through September: 39, 75% above the average of 22 for those months in 2008-2025. South Willamette Valley was covered most often (259 times since 2008).
How many dense fog advisories does Oregon get?
Every dense fog advisory that covered part of Oregon. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 39 |
| 2025 | 61 |
| 2024 | 94 |
| 2023 | 81 |
| 2022 | 71 |
| 2021 | 38 |
| 2020 | 57 |
| 2019 | 50 |
| 2018 | 44 |
| 2017 | 41 |
| 2016 | 35 |
| 2015 | 59 |
| 2014 | 54 |
| 2013 | 53 |
| 2012 | 16 |
| 2011 | 27 |
| 2010 | 31 |
| 2009 | 49 |
| 2008 | 32 |
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 Oregon 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 Oregon?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| South Willamette Valley | 259 | 35 | February 24, 2024 |
| Central Willamette Valley | 206 | 26 | February 13, 2024 |
| Oregon Lower Treasure Valley | 167 | 38 | January 15, 2026 |
| Greater Portland Metro Area | 150 | 17 | February 14, 2024 |
| Central Douglas County | 138 | 30 | February 5, 2026 |
| Jackson County | 135 | 28 | February 15, 2026 |
| Eastern Curry County and Josephine County | 128 | 26 | February 5, 2026 |
| Lower Columbia | 96 | 13 | February 13, 2024 |
| Foothills of the Northern Blue Mountains of Oregon | 85 | 47 | February 15, 2026 |
| Lane County Lowlands | 48 | 48 | March 2, 2026 |
| Lower Columbia Basin of Oregon | 48 | 21 | January 30, 2026 |
| Benton County Lowlands | 42 | 42 | March 2, 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 Oregon.