Carroll County

Every recorded tornado

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

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.

More event types since 1996

Costliest events since 1996

1. Jul 24, 2010Flash Flood$10.0 million
   National Weather Service narrative

   After about a foot of rain in 2 days, creek and small river basins rose rapidly Saturday morning. Numerous rural roads throughout the county suffered from washouts and excessive erosion. Near Argo Fay, Johnson Creek overflowed its banks and closed Big Cut Road.||In Mount Carroll, flooding of the Waukarusa River forced evacuations of about 80 homes, mainly on or near Mill Street. The local fire chief estimated that 80% of Mount Carroll residences had water in their basements.||The Plum River overflowed its banks between Lake Carroll and Savanna, causing extensive and severe damage. Just west of Lake Carroll, a farm house on Polsgrove Road flooded. The resident of the home described…

2. Jul 23, 2010Flash Flood$1.0 million
   National Weather Service narrative

   Heavy rains of 3 to 9 inches fell across Carroll County during the late evening hours of July 22 and through the morning hours of July 23 resulting in flash flooding of much of the county. Several roads across the county, especially the northern half, were closed due to the flash flooding. The Shannon area received over 8 inches of rain during the night and was in need of sludge pumps to assist with the flooding issues in the area. Areas that had never flooded before were flooded.

3. May 4, 2003High Wind, Carroll$1.0 million
   National Weather Service narrative

   numerous reports of limbs & power lines down

4. Jun 23, 1996Thunderstorm Wind$1.0 million
   National Weather Service narrative

   Thunderstorm winds destroyed a large warehouse.

5. Apr 5, 2010Thunderstorm Wind$750,000
   National Weather Service narrative

   Wind gusts estimated to be 70 mph caused a west-facing wall of a church to collapse in Milledgeville, IL around 858 pm April 5. In addition, several 3 foot diameter trees were blown down. Numerous power lines were also knocked down resulting in a power outage to much of the town. Most of the damage was across the northwest part of town and extended about 0.5 miles to the north.

6. Jul 28, 2011Flash Flood$250,000
   National Weather Service narrative

   A large breach in the Portland Avenue Levee on the Plum River caused some flash flooding in parts of Savanna, IL during the evening of July 28 and early morning hours of July 29.

7. Apr 17, 2013Flash Flood$250,000
   National Weather Service narrative

   Several rounds of heavy rains resulted in some flash flooding of much of Carroll County during the afternoon hours of April 17.

8. Jul 27, 2011Flash Flood$250,000
   National Weather Service narrative

   Torrential rains of 2 to 5 inches caused some flash flooding across the northern half of Carroll County during the late evening of July 27 and morning of July 28. Several streets in the town of Savanna were flooded forcing the evacuations of 80 residents. Portions of Mount Carroll along the Plum River were also flooded. Both railroad yards in the town were also underwater.

9. Apr 18, 2011Flood$250,000
   National Weather Service narrative

   Water from snow-melt in the upper Midwest moved south through the Mississippi River basin causing major flooding along the Mississippi River.||The snowfall was well above normal for the 2010-11 winter in much of Minnesota and Wisconsin. Minneapolis, MN recorded 86.6 inches of snow, which is 30 inches above normal. Snowfall in eastern Iowa, northwest Illinois, and northeast Missouri totaled 35 to 65 inches, which was 10 to 20 inches above normal.||The snow-melt flood crest reached Dubuque on April 19 and was finally south of the Burlington area by April 25. The crest levels ranked 4th through 8th depending on the location, when compared to historical crests.||Bellevue surpassed its…

10. Jul 5, 2003Thunderstorm Wind$200,000
    National Weather Service narrative

    Numerous limbs down; house under construction had roof torn off

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

108°FJul 12, 1936

All-time low

−38°FJan 31, 2019

Warmest night

84°FJul 20, 1930

Coldest day

−12°FDec 25, 1983

Wettest day

6.96 inJun 4, 2002

Snowiest day

12.5 inFeb 10, 1960

Hottest year

1921mean 52.8°F

Coldest year

1989mean 42.9°F

Wettest year

201553.71 in

Driest year

190117.31 in

Snowiest season

77.5 in1978-79

Station Mount Carroll (USC00115901), 708 ft elevation, 2.2 miles from the population centre. Daily records from 1897 to October 27, 2026; 97.8% 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 USC00115901.
• 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.