Washington County, Oregon

What hazards hit Washington County most?

The most frequent records are high wind and dust records: 276 since 1996. 44% of its high wind and dust records since 1996 fell in January and February. The rank column places the county among Oregon's counties by days with a record per 1,000 square miles of land over each hazard's complete period.

Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.

How many tornadoes has Washington County had?

NOAA records 6 tornadoes in Washington County from 1954 to 2018, the strongest rated F1, with 0 deaths and 0 injuries recorded in the county. That is 3rd of 36 Oregon counties by days with tornadoes per 1,000 square miles since 1950. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.

Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 7 tornadoes whose track touched Washington County since 1950 (NOAA's county records number 6: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 0 people.

Map of the strongest tornado tracks in Oregon.

Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.

When was the last damaging storm in Washington County?

The most recent record with damage, injuries or deaths is the July 9, 2024 heat (4 deaths).

The hottest period was from the 5th to 9th where high temperatures ranged from 98 to 103 at Hillsboro Airport in the Tualatin Valley. In addition to the hot daytime temperatures, overnight low temperatures were well into the 60s offering little cooling for those without air conditioning. The normal high is around 80 degrees and the normal low is around 51 degrees. The State Medical Examiners reported 4 suspected heat related fatalities in this zone.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1204268)

Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.

The deadliest and costliest records

Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.

Is it getting more frequent?

Records per decade for Washington County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).

Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).

What time of year?

44% of its high wind and dust records since 1996 fell in January and February. The two busiest months are in violet.

Source: NOAA NCEI Storm Events Database, records by the month they began.

Federal disaster declarations for Washington County

FEMA's register lists 17 declarations that include Washington County: 11 major disasters, 3 emergencies and 3 fire management assistance declarations. Most were for fire (5) and severe storm (4).

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.

How many floods has Washington County had?

NOAA's Storm Events Database holds 52 flood or flash flood records for Washington County from 1996 to 2024, on 44 days, with 3 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Washington County ranks 592nd of 2,942 U.S. counties.

The National Flood Insurance Program has paid $5.5 million on 408 claims filed in Washington County; the most in one year was 179 in 1996. Claims count insured losses only: uninsured flood damage is not in this file.

Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.

FEMA's modeled risk for Washington County

FEMA's National Risk Index rates Washington County Relatively High overall, with an expected annual loss of $270 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.

Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.

Counties that share a border with Washington County

1. Tillamook County 886
2. Clackamas County 875
3. Clatsop County 832
4. Washington County 577
5. Multnomah County 521
6. Yamhill County 456
7. Columbia County 412

Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.

Next

• Tornadoes in OregonEvery Oregon tornado since 1950 and the counties with the most per square mile
• High wind and dust storms in OregonThe state's high wind and dust records, by county, year and month
• The Oregon recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in Washington CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Washington County's FEMA declarations (CSV)17 rows: every declaration that named the county, for your own analysis