Ada County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Ada County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every large fire

1. Large fires mapped by the Monitoring Trends in Burn Severity program since 1984: 1,000 acres or more in the West, 500 or more in the East. Prescribed burns are excluded. Acres here are the part of each perimeter inside this place.

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service), 1984 to 2026.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

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).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Volcanoes within 100 miles

1. U.S. volcanoes within 100 miles, from the USGS Volcano Hazards Program. The threat category is the USGS 2018 National Volcanic Threat Assessment, which ranks volcanoes by how hazardous their past eruptions were and how many people and how much infrastructure lie near them. It is not a forecast of eruption.

USGS Volcano Hazards Program, retrieved October 30, 2026.

Mapped landslides

Mapped by ID GS (77), NASA (2).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Aug 25, 2008Wildfire, Upper Treasure Valley$5.0 million
   National Weather Service narrative

   A wildfire in Southeast Boise caused by an electrical component near an Idaho Power sub station quickly burned out of control destroying 10 homes and damaging many more including 1 fatality. Another wildfire near Mountain Home burned around 500 acres.

2. May 1, 2017Flood$2.0 million
   National Weather Service narrative

   The Boise River remained in flood during the entire month of May due to planned release from Lucky Peak dam. Regulated flows were above flood stage for 101 days resulting in extensive damage to the Greenbelt and Nature Trail paths. Extensive flood fight efforts continued in the Eagle Island area to prevent a pit capture. Widespread flooding continued on Eagle Island in the Riviera Estates area where several homes were surrounded by water and low lying roads were inundated. Large portions of Ann Morrison Park, Barber Park, and Marianne Williams Park were impacted by flood waters. Some residential streets continued to be impacted by flood waters, especially in the Garden City…

3. Mar 6, 2017Flood$1.0 million
   National Weather Service narrative

   The Army Corps of Engineers and Bureau of Reclamation increased regulated flows from Lucky Peak Reservoir putting the Boise River in flood for the remainder of the month of March. Flooding was expected to continue through late spring. Flood flows for the extended period caused significant damage to much of the Greenbelt and Nature Trail paths along the river. Flood fight efforts were focused in the Eagle Island area where severe bank erosion occurred and a pit capture threat existed. A HESCO barrier wall and extensive sandbagging occurred in the area to mitigate a pit capture.

4. Apr 1, 2017Flood$1.0 million
   National Weather Service narrative

   Planned releases from Lucky Peak Reservoir for flood control ranged from 7800 CFS to 8900 CFS during the month of April. The prolonged flood flows continued to cause extensive damage to the Greenbelt and Nature Trail paths. Flood waters inundated portions of Eagle Island, particularly along Artesian Road and Hatchery Road. Numerous homes in Riviera Estates were surrounded by water. Flood fight efforts continued to focus in the Eagle Island area with extensive sandbagging taking place. Additional flood fight efforts to mitigate a pit capture continued along the Eagle Island south channel of the river. Flood diversion tubes and muscle wall barriers were used to limit river…

5. Jun 6, 2023Flash Flood$1.0 million
   National Weather Service narrative

   Thunderstorms produced heavy rain across portions of the Lower Treasure Valley, including the city of Boise. Social media, weather spotter, and emergency manager reports indicated localized flooding.

6. Jul 28, 2010Wildfire, Upper Treasure Valley$500,000
   National Weather Service narrative

   The Boise District BLM reported a wildfire in the foothills near Eagle, Idaho. Lightning sparked a grass fire east of Linder and Homer roads and burned approximately 5000 acres and 5 structures including 3 homes.

7. Mar 29, 2009High Wind, Upper Treasure Valley$100,000
   National Weather Service narrative

   The Boise NWS ASOS recorded a peak gust of 53 MPH and over $100,000 in damages were sustained in the north end of Boise while Mountain Home had winds of 40 to 50 MPH for most of the day.

8. Aug 21, 2010Wildfire, Upper Treasure Valley$100,000
   National Weather Service narrative

   A home and six out buildings were destroyed by a wildfire due to downed power lines in the area of Federal Way and Kootenai streets.

9. Sep 11, 1997Flash Flood$60,000
   National Weather Service narrative

   During the evening of September 11, a flash flood occurred in the foothills of the Boise Mountains. The foothills had received significant rainfall all day long. Between 500 pm and 600 pm MST a heavy shower dumped 4 tenths of an inch of rain in 9 minutes on the foothills triggering flash flooding into the north end of Boise. The wall of mud and debris was estimated at 15 feet high as it breached six flood control dams and washed over a golf course. While most of the damage consisted of mud and debris on local roadways, the golf course sustained damage and 12 houses were slightly damaged at the foundations. No injuries were reported. As of publishing , damages to roads in the city…

10. Sep 7, 1998Thunderstorm Wind$20,000
    National Weather Service narrative

    Scattered thunderstorms produced heavy rains and isolated wet microbursts in the Boise area. Numerous reports of street flooding were received from around the city. Lightning caused a structure fire in Boise while about 3000 people were without power due to trees falling on power lines. At Shadow Valley on the outskirts of Boise, winds ripped two sections of roof off of an elementary school.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

111°FJul 19, 1960

All-time low

−25°FDec 22, 1990

Warmest night

82°FJul 22, 2024

Coldest day

−6°FDec 22, 1990

Wettest day

1.91 inJun 12, 1958

Snowiest day

9.8 inDec 20, 1996

Hottest year

2025mean 55.5°F

Coldest year

1985mean 45.9°F

Wettest year

198318.77 in

Driest year

19666.64 in

Snowiest season

48.8 in1948-49

Station Boise Air Terminal (USW00024131), 2,823 ft elevation, 4.8 miles from the population centre. Daily records from 1940 to October 26, 2026; 100.0% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

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).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00024131.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Volcanoes USGS Volcano Hazards Program, U.S. volcanoes and 2018 threat assessment.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.