Canyon County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Canyon 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.

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 (6).

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. Jan 18, 2017Heavy Snow, Lower Treasure Valley$100 million
   National Weather Service narrative

   Numerous reports from social media reported 6 to 9 inches of snow around Caldwell and 15 to 16 inches from Ontario to Payette and Weiser reported by emergency management. Significant damage occurred to agricultural buildings housing fresh produce.

2. Jun 26, 2026Flash Flood$7.0 million
   National Weather Service narrative

   Timing estimated by MRMS, polygon focused on the area with the largest impact and intentionally kept broad. Numerous reports received of flooded roadways, some impassable; flooding also affected houses, public buildings, and infrastructure. The Caldwell Airport ASOS reported 1.06 inches of rainfall having fell in 15 minutes. A disaster was declared for Canyon County in the aftermath. There was an estimated 7 million dollars in damages to infrastructure.

3. May 1, 2017Flood$750,000
   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 bank erosion and flooding of lowlands along the river.

4. Apr 1, 2017Flood$500,000
   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 caused extensive damage along the river banks and widespread flooding of lowlands.

5. Aug 26, 1996Thunderstorm Wind$250,000
   National Weather Service narrative

   Thunderstorms moved through Southwestern Idaho with strong winds and lightning. Several locations reported downed trees and power lines. The hardest hit area was Nampa in Canyon county. Wind lifted a dairy barn and smashed it, several roofs were pulled off of houses, barns and sheds were blown over, large trees were uprooted, one fell on a house, and several residents reported small grass and barn fires. 911 in Canyon county had a record number of calls. Several fires were ignited by lightning. In the Vale District, 16 fires were started totalling 26000 acres. In Owyhee county, reports of visiblity reduced to zero in blowing dust occured at Givens Hot Springs.

6. Mar 6, 2017Flood$250,000
   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. The extended period of flood flows caused severe bank erosion and lowland flooding.

7. Apr 24, 2003Thunderstorm Wind$100,000
   National Weather Service narrative

   A cold front moving through the area had strong convection embedded along the leading edge. A strong downburst from a cell moving through the Middleton area produced the damaging winds in the vicinity of the Middleton High School.

8. May 6, 2005Flash Flood$50,000
   National Weather Service narrative

   Flooding at the Caldwell Airport, parts of Caldwell, Conway Rd washed out

9. May 17, 1996Tornado$50,000
10. Jun 15, 1999Thunderstorm Wind$40,000
    National Weather Service narrative

    Scattered thunderstorms moved through southern Canyon and western Ada counties and produced damaging wind gusts. Numerous trees and powerlines were downed throughout the area. A 75 foot tall tree fell on a home in Nampa and a porch was torn off another home. In Boise, the I-84 connector was closed due to downed powerlines.

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, 19.5 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.