Rock County

Every recorded tornado

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

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.

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, 2013Winter Storm, Rock$10.0 million
   National Weather Service narrative

   An extended period of precipitation began with freezing rain quickly producing heavy ice accumulations, ranging up to a half inch. The precipitation then changed to sleet and then snow, with sleet and snow accumulations reaching 6.7 inches at Luverne. Many branches, limbs, whole trees, and power lines were downed by the weight of ice and accompanying wind. Both urban areas and rural electric cooperatives suffered major power line damage. Trees and tree debris blocked many roads, and damaged several vehicles and homes. Major power outages were reported, affecting thousands of people. The winter precipitation made travel impossible in many areas, resulting in schools and businesses…

2. Jun 14, 2014Flash Flood$3.0 million
   National Weather Service narrative

   In the midst of very heavy rain, estimated as much as 7 inches, a dam partially gave way on Blue Mounds Creek at Blue Mounds Lake in Blue Mounds State Park. The dam break drained the lake and flooded roads downstream to the Rock River.

3. Jun 21, 2024Flood$2.0 million
   National Weather Service narrative

   Rainfall amounts across Rock County from June 20-22 ranged from 2 to 7 inches. Widespread overland flooding ensued with additional moderate to major flooding along the Rock River and Split Rock Creek.||During peak flooding, numerous township, county, and state roads were under water and closed. A No Travel Advisory was issued by law enforcement. Interstate 90 was under water and briefly closed between Luverne and Worthington where a swift water rescue was conducted near mile marker 17. U.S. Highway 75 was also closed from Luverne to the Iowa state line. ||In Luverne, numerous roads were reported under water and flood waters from the Rock River inundated Redbird Field and the…

4. Aug 3, 2004Thunderstorm Wind$2.0 million
   National Weather Service narrative

   Thunderstorm winds blew down part of the roof of a large store, destroyed a hangar, and damaged a small plane inside. The winds also blew down signs including a large gas station sign, blew down the roof of a hardware store shed onto a pickup parked inside and destroyed several storage sheds and other small structures. Parts of roofs of several homes and garages were blown off or damaged. The winds caused widespread tree damage, with falling trees or debris damaging several homes and vehicles, and debris blocking several roads. Power lines and poles were blown down, causing power outages, and several light poles were also blown down. The winds also caused severe crop damage in the…

5. Nov 14, 1996Ice Storm, Rock$1.5 million
   National Weather Service narrative

   An ice storm consisting of several periods of freezing rain caused widespread damage to power lines and poles, and to trees. Power lines snapped, cable wires were ripped down, and tree debris littered and blocked some roads. Thousands lost power, some for 5 days. Travel was curtailed by icy surfaces and there were numerous accidents, although no serious injuries were reported. The ice storm was described as the worst in 40 years in the Worthington area. Many small farm structures were damaged. A 600 foot radio tower in Worthington was toppled. Schools and business were forced to close. Damage continued after the ice storm ended, including some damage occurring when ice melted…

6. Apr 13, 2018Thunderstorm Wind$728,000
   National Weather Service narrative

   Numerous power poles down along I-90 and either side at Magnolia exit.

7. Apr 10, 2019Ice Storm, Rock$602,000
   National Weather Service narrative

   Ice accumulated to one-half to three quarters of an inch. As winds increased during the night of April 10 into early April 11 with gusts reaching 40 to 50 mph at times, power poles and transmission lines bore the brunt of the worst conditions. Warming shelters were set up in several communities which were without power for a day or two, due to more than 100 power poles snapped by the weight of the ice accumulation and stress of the high winds. Damage costs are rough estimates due to utility costs.

8. Mar 13, 2019Flood$215,000
   National Weather Service narrative

   Water flowed over multiple areas of U.S. Highway 71, mainly in areas east of Steen and near Hardwick. Numerous other county and township roads were covered by water at times. The property damage costs include estimates for public property losses.

9. Apr 6, 2019Flood$215,000
   National Weather Service narrative

   Runoff from occasional precipitation in late March and early April produced considerable flooding of agricultural land. Other than a brief period from 0600CST April 26 to 1300CST April 27, the river remained in flood through the end of the month. Split Rock Creek below Jasper (gage site JSPM5) crested in major flood stage (5.49 feet above flood stage) on April 7, the third highest crest on record. A second crest in moderate flood stage occurred on April 17 at 3.79 feet above flood stage. Minor flooding continued at the end of the month.

10. Jun 15, 2014Flood$200,000
    National Weather Service narrative

    Repeated heavy rains caused record flooding of the Rock River. Numerous roads and some homes and businesses were flooded in Hardwick and Luverne. Farmland and other lowlands along the river were also flooded. In Luverne the flooding included parkland and part of Interstate 90, which was closed by the flooding. A dam break at Blue Mounds Lake in Blue Mounds State Park was determined to have added slightly to the flooding at Luverne. The river crested at a record 7.18 feet above flood stage at Hardwick, and at a record 6.85 feet above flood stage at Luverne, both on June 17th.

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

110°F2 times, most recently Jun 21, 1988

All-time low

−36°FJan 19, 1970

Warmest night

81°F3 times, most recently Aug 22, 2023

Coldest day

−17°FFeb 8, 1933

Wettest day

5.44 inAug 7, 2022

Snowiest day

18.1 inMar 10, 1956

Hottest year

2012mean 50.6°F

Coldest year

1950mean 42.3°F

Wettest year

201939.54 in

Driest year

197611.42 in

Snowiest season

94.7 in1968-69

Station Sioux Falls (USW00014944), 1,495 ft elevation, 25.0 miles from the population centre. Daily records from 1932 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 USW00014944.
• 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.