DeKalb County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within DeKalb County: 2.
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.

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.

More event types since 1996

Costliest events since 1996

1. Apr 9, 2015Tornado$8.0 million
   National Weather Service narrative

   This is the third segment of the Rochelle-Fairdale EF-4 tornado. At its strongest, peak winds were estimated to be 200 mph. The tornado entered the county just southwest of Fairdale before directly hitting the small community. Peak winds were estimated at 165 mph in Dekalb County, rating this section of the tornado a high end EF-3. Approximately 71 homes in the community had been damaged, 17 of which had been completely destroyed with all walls collapsed or removed from the buildings. Some homes that were only nailed to the foundation were swept clean. Two fatalities and 11 injuries occurred in Fairdale. A 67-year-old woman and her neighbor, a 69-year-old woman, were both killed…

2. Sep 14, 2008Flash Flood$3.0 million
   National Weather Service narrative

   Flash flooding or significant flooding was reported across much of DeKalb County, including street closures due to flooding, basement flooding and creek, stream and river flooding. Extensive flooding was reported in the Evergreen mobile home park near Sycamore. Street flooding was reported in Waterman, Hinckley and Shabbona.

3. Aug 23, 2007Flood$1.0 million
   National Weather Service narrative

   After flash flooding from heavy rainfall on the evening of August 23rd, significant flooding continued across parts of central DeKalb County as rivers and streams overflowed their banks and flood waters took days to subside. During the morning of August 24th, Route 30 and 1st Street were impassable. A mobile home park was evacuated due to flood waters and Highway 64 was flooded with two feet of standing water. Flood waters inundated the Northern Illinois University campus and surrounding areas. Levees on campus were overtopped as water levels rose. Students from NIU helped sandbag in an attempt to hold back floodwaters. Roads and streets were closed due to flooding throughout…

4. Jul 9, 2007Flash Flood$750,000
   National Weather Service narrative

   Torrential rainfall led to flash flooding in parts of DeKalb. Numerous roads were closed with four feet of standing water. Several people had to be rescued from cars in high water. Numerous basements were flooded and a retail store on Sycamore Street was flooded. A dorm on the Northern Illinois University Campus was evacuated. Rainfall amounts ranged from 3 to 5 inches across DeKalb. The highest amount was 5.00 inches at 13th and Scyamore Street, before the gage overflowed.

5. Aug 23, 2007Flash Flood$500,000
   National Weather Service narrative

   Kishwaukee River flooding houses and apartments.

6. May 20, 2014Thunderstorm Wind$500,000
   National Weather Service narrative

   An approximately seven mile swath of damage occurred on the south side of Dekalb which was consistent with 60 mph to occasionally 100 mph winds. Damage began near the intersection of Malta Road and Nelson Road and concluded near Lynch Road just south of Gurler Road. A warehouse on Harvestore Drive had a portion of the roof torn off along with a broken window. Some mobile homes in the parking lot were rolled or overturned.

7. Aug 23, 2007Flash Flood$500,000
   National Weather Service narrative

   Extensive flooding of buildings at the Northern Illinois Univeristy campus.

8. Sep 22, 2006Thunderstorm Wind$200,000
   National Weather Service narrative

   Six, 75 foot tall power transmission poles were blown down and several trees were also blown down. Corn fields were flattened by wind.

9. Jun 12, 2008Thunderstorm Wind$100,000
   National Weather Service narrative

   The roof of a one story house was completely blown off and the east wall of the house was also blown down on Irene Road, about 2 miles south of Route 72. Trees were also blown down.

10. Jul 24, 2010Flash Flood$100,000
    National Weather Service narrative

    Very heavy rain fell across north central De Kalb County during the early morning hours of July 24th producing widespread flooding and flash flooding. Street and basement flooding was reported. A trailer park in Sycamore was evacuated with almost 8 inches of rainfall reported in Sycamore. Many roads were flooded and closed in Sycamore. Route 72 was flooded in Kirkland. Storm total rainfall of 5.46 inches was measured two miles southwest of Genoa.

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

103°FAug 17, 1988

All-time low

−27°FJan 20, 1985

Warmest night

79°F2 times, most recently Jul 13, 1981

Coldest day

−14°F2 times, most recently Jan 31, 2019

Wettest day

8.09 inJul 18, 1996

Snowiest day

15.7 inFeb 2, 2011

Hottest year

2005mean 52.7°F

Coldest year

2014mean 45.2°F

Wettest year

197249.64 in

Driest year

200521.48 in

Snowiest season

80.3 in1978-79

Station De Kalb (USC00112223), 878 ft elevation, 2.5 miles from the population centre. Daily records from 1966 to October 27, 2026; 98.3% 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 USC00112223.
• 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.
• 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.