Washtenaw County, Michigan: Natural Disaster Risk and History
Washtenaw County, Michigan has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 89.3 out of 100, higher than about 89% of US counties, with strong winds, tornadoes and cold waves scoring highest of its 18 hazards and $93 million a year in expected losses.
OpenFEMA lists 10 federal disaster declarations that included Washtenaw County since 1965, not counting 2 for COVID-19; the latest is DR-4925-MI (Severe Storms, Tornadoes, and Flooding, declared 30 June 2026). NOAA's Storm Prediction Center recorded 28 tornadoes touching Washtenaw County from 1950 to 2025.
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Population 372,064 Buildings worth $89 billion Area 730 sq mi Risk rank in Michigan 6 of 83 FIPS 26161
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Strong wind | Relatively High | 98.0 | $6.1 million | about 5.7 a year | 217 |
| Tornado | Relatively High | 96.9 | $21 million | about once every 2.9 years | 20 |
| Cold wave | Relatively High | 93.1 | $11 million | about 2.8 a year | 53 |
| Ice storm | Relatively High | 90.4 | $1.2 million | about 1.8 a year | 120 |
| Inland flooding | Relatively Moderate | 90.3 | $47 million | about 1.2 a year | 33 |
| Lightning | Relatively High | 88.8 | $1.3 million | about 37 a year | 247,816 strikes |
| Heat wave | Relatively Moderate | 87.4 | $2.9 million | about 3.7 a year | 56 |
| Hail | Relatively Moderate | 85.8 | $1.5 million | about 3.1 a year | 119 |
| Earthquake | Relatively Low | 74.3 | $1.3 million | rarer than once in 1,000 years | — |
| Winter weather | Relatively Moderate | 73.0 | $178,527 | about 11 a year | 199 |
| Landslide | Relatively Low | 69.9 | $7,028 | about once every 5.4 years | — |
| Hurricane | Very Low | 48.3 | $73,315 | about once every 112 years | 2 |
| Wildfire | Very Low | 43.8 | $38,200 | rarer than once in 1,000 years | — |
| Drought | No Rating | 0.0 | — | — | 0 |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 10
Most common: Snowstorm 3, Flood 2, Severe Storm 2, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 1 | Tornado |
| 1970s | 1 | Snowstorm |
| 1980s | 1 | Flood |
| 1990s | 1 | Snowstorm |
| 2000s | 4 | Hurricane, Severe Storm, Other, Snowstorm |
| 2020s | 2 | Flood, Severe Storm |
The last 10
Widest declarations that included Washtenaw County
- Hurricane Katrina Evacuation (2005, EM-3225-MI): 83 Michigan counties designated.
- Blizzards & Snowstorms (1978, EM-3057-MI): 83 Michigan counties designated.
- Snow (2001, EM-3160-MI): 39 Michigan counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Michigan also had 3 statewide declarations with no county list.
Tornado record since 1950 28
| Tornadoes touching the county | 28 |
|---|---|
| Strongest-rated | (E)F3 ×4 |
| Peak month | June (8) |
| Deadliest | 8 Jun 1953, F3, 11.3 mi path, 1 killed, 5 injured |
| Longest path | 13 Jun 1994, F2, 16 mi path, 0 killed, 2 injured |
| Most recent | 22 Jun 2015, EF1, 4.3 mi path |
| Deaths / injuries on those paths | 2 / 63 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 8 | 10 | 6 | 4 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 3 | 4 | 5 | 8 | 2 | 2 | 4 | 0 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Washtenaw County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Washtenaw County (this page) | — | Relatively Moderate | 89.3 | Strong wind |
| Livingston County | 39 km | Relatively Low | 73.5 | Strong wind |
| Monroe County | 44 km | Relatively Moderate | 82.5 | Strong wind |
| Lenawee County | 44 km | Relatively Low | 69.9 | Strong wind |
| Wayne County | 46 km | Relatively High | 99.0 | Cold wave |
| Jackson County | 48 km | Relatively Low | 76.5 | Tornado |
Nearest by distance between county centres. Every county in Michigan, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 21.5 |
|---|---|
| Community resilience | Very High 97.0 |
| Community risk factor | 0.89 |
| Expected annual loss, all hazards | $93 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Washtenaw County's main hazards
- Right now: National Weather Service alerts for Michigan · all official warnings on Global Incident Tracker.
- Strong wind: Power outages now
- Tornado: Is there a tornado warning now?
- Cold wave: Carbon monoxide in winter · Power outages now
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Washtenaw County
What natural disasters is Washtenaw County, Michigan most at risk from?
Washtenaw County, Michigan has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 89.3 out of 100, higher than about 89% of US counties, with strong winds, tornadoes and cold waves scoring highest of its 18 hazards and $93 million a year in expected losses.
How many federal disaster declarations has Washtenaw County had?
OpenFEMA lists 10 federal disaster declarations that included Washtenaw County since 1965, not counting 2 for COVID-19; the latest is DR-4925-MI (Severe Storms, Tornadoes, and Flooding, declared 30 June 2026). Another 3 Michigan declarations were made statewide without a county list.
How many tornadoes have hit Washtenaw County?
NOAA's Storm Prediction Center recorded 28 tornadoes touching Washtenaw County from 1950 to 2025. The deadliest: 8 Jun 1953, F3, 11.3 mi path, 1 killed, 5 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.