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Ada County, Idaho

Natural disaster risk, federal disaster history and flood insurance facts.

Relatively Moderate overall risk
1st of 44highest risk in Idaho
$116Mexpected losses a year
4federal declarations
1 in 111homes with flood insurance
Photo: Pavel Špindler, CC BY 3.0

Ada County, Idaho has a moderate overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 88% of US counties. It ranks 1st of 44 counties in Idaho. The costliest hazards here are inland flooding, wildfires and heat waves. FEMA estimates about $116 million a year in expected losses, or roughly $234 per resident. Since 1964 it has been included in 4 federal disaster or emergency declarations for natural events (3 major disasters). The most recent was in October 2017 (flooding). Fewer than 1 in 100 homes here carry federal flood insurance (1,541 policies). Since 1978, federal flood insurance has paid about $499,000 on 133 claims here.

FEMA National Risk Index December 2025; OpenFEMA declarations to Nov 6, 2026; NFIP records. Updated November 6, 2026.

Top risks in Ada County

$63 million a yearExpected losses. Damaging events about once a year.
  • Check the FEMA flood map for your address, and ask the seller or landlord about past flooding.
  • Price a flood policy now. Most new federal policies take 30 days to start.
$26.6 million a yearExpected losses. Damaging events about once every 85 years.
  • Clear dry plants and debris within 5 feet of the house.
  • Get home insurance quotes early; availability varies by area.

Heat wave

Moderate
$7 million a yearExpected losses. Damaging events about 4 times a year.
  • Check that cooling works before summer.
  • Know where the nearest cooling center is.
HazardRatingScoreExpected loss a year
Inland floodingModerate89.8
$63M
WildfireHigh98.3
$27M
Heat waveModerate92.9
$7M
EarthquakeLow88.2
$7M
Strong windHigh91.8
$4M
Winter weatherVery High98.9
$3M
LightningHigh90.1
$2M
Cold waveLow51.7
$2M
Ice stormModerate80.5
$706K
TornadoLow27.0
$686K
HailLow54.5
$525K
LandslideLow69.1
$9K
DroughtVery Low14.6
$783
Volcanic activityVery Low74.3
$235
AvalancheVery Low27.0
$132

Scores are percentiles: a score of 90 means higher risk than about 90% of US counties for that hazard. Hazards FEMA does not rate here are left out. Social vulnerability is very low and community resilience is very high in FEMA's measures.

Federal disaster history

Recent disasters nationwide ›

Declarations by decade

Federal declarations for natural events that included Ada County. 2020s bar runs to November 2026.

By type

Flood2
Fire1
Hurricane1

Most recent

Oct 7, 2017FloodingMajor disaster
Sep 13, 2005Hurricane KatrinaEmergency
Sep 1, 2000WildfiresMajor disaster
Dec 31, 1964Heavy Rains & FloodingMajor disaster

Idaho also had 16 statewide declarations that did not name single counties.

Storm history since 1956

Tornado risk by county ›

The National Weather Service has logged 218 storm reports in Ada County since 1956, with 0 deaths and 77 injuries and about $6.7 million in reported damage. The strongest on record here was an F1 tornado on October 26, 1984.

13tornadoes
41hail reports, largest 1.5 inches
117damaging thunderstorm winds
23floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Oct 26, 1984F1–0 / 0
Mar 21, 1984F1–0 / 0
Jul 9, 1956F1–0 / 0
Aug 23, 1956F0–0 / 0
Apr 20, 1997F0Boise Terminal Arpt0 / 0

Most damaging storms

DateTypeNearDamage
May 1, 2017FloodBarber$2M
Jun 6, 2023Flash FloodBoise$2M
Apr 1, 2017FloodBarber$1M
Mar 6, 2017FloodBarber$1M
Apr 27, 1995Thunderstorm WindStar$500K
Sep 11, 1997Flash FloodBoise$60K

Source: NOAA Storm Events Database, county-based reports through May 28, 2026. Tornado records start in 1950, hail and wind in 1955, and floods and other storm types in 1996, so older decades undercount. Damage is in dollars of the year it happened and is often an estimate. Winter storms, heat and hurricanes are logged by forecast zone, not county, so they are not counted here.

Flood insurance in Ada County

Check your address flood zone ›
0.9%of homes have federal flood insurance (1,541 policies)
25.2%of homes in mapped high-risk flood zones are insured
$498,925paid on 133 flood claims since 1978
2017costliest year, with $267,509 paid

National Flood Insurance Program (NFIP) records only; private flood policies are not included. Home counts as of Aug 3, 2026. Since 2021 NFIP prices each home separately under Risk Rating 2.0, so your price depends on the building, not the county. Ask an agent for a quote.

Homes in Ada County

$512,300median home value (Idaho $418,600, US $332,700)
1997median year homes were built (Idaho 1991, US 1980)
28%of homes built before 1980, before many modern wind, quake and flood building rules
2.7%of homes are mobile homes, which are the least safe in tornadoes and high winds

Older homes and mobile homes usually suffer more damage in storms, floods and earthquakes, and can cost more to insure. If you are buying, ask about roof age, foundation bolting and any retrofits. Source: US Census Bureau, American Community Survey 2020 to 2024 5-year estimates; 211,440 housing units.

Compare in Idaho

All 44 ›
Largest countiesOverall riskTop hazard
Ada CountyModerateInland flooding
Canyon CountyLowInland flooding
Kootenai CountyLowInland flooding
Bonneville CountyModerateInland flooding
Twin Falls CountyLowInland flooding
Bannock CountyLowWildfire
Madison CountyLowInland flooding
Bingham CountyLowInland flooding

Neighboring counties

CountyOverall riskDeclarations
Canyon CountyLow2
Elmore CountyLow9
Gem CountyVery Low5
Owyhee CountyLow4
Boise CountyLow5

Common questions about Ada County

What is the biggest natural hazard in Ada County?

Inland flooding has the highest expected yearly losses in Ada County, about $63 million a year in FEMA's estimate. Wildfire is second at $26.6 million.

How many federal disasters has Ada County had?

Ada County has been included in 4 federal disaster or emergency declarations for natural events since 1964, including 3 major disasters. The most recent was Flooding in October 2017.

Is Ada County a high-risk place to live?

Its overall rating is Relatively Moderate, 1st highest of 44 in Idaho. A county rating covers the whole area. Risk at one address can be much higher or lower, so check the FEMA flood map and ask about the home's history.

Do I need flood insurance in Ada County?

Standard home insurance does not cover flooding. About 1 in 111 homes in Ada County has federal flood insurance. Lenders require it in mapped high-risk zones, but many flood claims come from outside those zones.

How many tornadoes has Ada County had?

NOAA records list 13 tornadoes in Ada County since 1950. The strongest was an F1 tornado on October 26, 1984. The weather service has also logged 41 hail reports and 23 floods here.

Sources: FEMA National Risk Index (December 2025), OpenFEMA Disaster Declarations Summaries, and NFIP policy and claims data. Hazard Compass is independent and not affiliated with FEMA. These figures describe the whole county, not a single property, and are not insurance or safety advice. Report a problem.