Boone County, Illinois

What hazards hit Boone County most?

The most frequent records are severe thunderstorm wind events: 143 since 1972. 53% of its severe thunderstorm wind events since 1972 fell in June and July. The rank column places the county among Illinois'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 Boone County had?

NOAA records 25 tornadoes in Boone County from 1959 to 2025, the strongest rated F4, with 25 deaths and 454 injuries recorded in the county. That is 17th of 102 Illinois counties and 252nd of 3,080 U.S. 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 25 tornadoes whose track touched Boone County since 1950 (NOAA's county records number 25, the same count); along their whole tracks they killed 28 people, 25 of them in Boone County.

Map of the strongest tornado tracks in Illinois.

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 Boone County?

The most recent record with damage, injuries or deaths is the March 31, 2023 tornado (1 death and 40 injuries).

This tornado crossed into Boone County south of Cherry Valley from Winnebago County. The tornado, which originated in Ogle County, traversed northeastward doing minor damage to farms. As it moved through the town of Belvidere, the storm produced multiple instances of damage to businesses, homes, and trees. Included in this is the partial roof collapse of the Apollo Theatre downtown which resulted in one fatality and 40 injuries. From there, the tornado would travel another 7 miles doing additional damage to trees before lifting near Orth Rd just west of the Boone-McHenry county line.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1085836)

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

A damage figure marked "step" is a record from before 1993: NOAA then filed damage by category, and the figure is the category as entered, in the dollars of that year, not an estimate of the loss.

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 Boone 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?

53% of its severe thunderstorm wind events since 1972 fell in June and July. The two busiest months are in violet.

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

Federal disaster declarations for Boone County

FEMA's register lists 11 declarations that include Boone County: 5 major disasters, 6 emergencies and 0 fire management assistance declarations. Most were for snowstorm (5) and biological (2).

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 Boone County had?

NOAA's Storm Events Database holds 35 flood or flash flood records for Boone County from 1996 to 2026, on 30 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Boone County ranks 1694th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $271,000 on 46 claims filed in Boone County; the most in one year was 6 in 1999. 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 Boone County

FEMA's National Risk Index rates Boone County Relatively Low overall, with an expected annual loss of $21.4 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 Boone County

1. Rock County, WI 1,215
2. Walworth County, WI 1,038
3. McHenry County 941
4. Winnebago County 888
5. DeKalb County 654
6. Ogle County 602
7. Boone County 419

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 IllinoisEvery Illinois tornado since 1950 and the counties with the most per square mile
• Severe thunderstorm wind in IllinoisThe state's severe thunderstorm wind events, by county, year and month
• The Illinois recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in Boone CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Boone County's FEMA declarations (CSV)11 rows: every declaration that named the county, for your own analysis