Hancock County

Every recorded tornado

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

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.

More event types since 1996

Costliest events since 1996

1. Aug 1, 2003Drought, Hancock$12.7 million
   National Weather Service narrative

   Dry weather settled in over Iowa during the month. The last widespread rain occurred on 09 July. With the increasingly dry conditions became a primary concern as the month progressed. An extended period of heat and humidity from the 15th to 25th saw highs into the 90s to over 100 degrees F. in some locations. By month's end drought indices had worsened to severe to extreme drought across south central Iowa and at least moderate drought over the remainder of the HSA. Waterloo had its driest August on record, Des Moines its 3rd driest and Ottumwa its 8th driest. A cold front brought only a brief respite from the intense heat, as temperatures rebounded into the 90s to near 100…

2. Nov 10, 1998High Wind, Hancock$300,000
   National Weather Service narrative

   Iowa experienced the worst November storm system since the great storm of 9 and 10 November 1975. During the 9th, low pressure developed over southeast Colorado. The low moved across Kansas during the afternoon and evening of the 9th and deepened to about 990 mb. Warm and moist air was drawn north ahead of the low resulting in widespread across the state. Thunderstorms erupted during the late evening of the 9th, though no severe weather occurred. During the predawn hours of the 10th, a jet streak rotated around the base of the upper level low pressure area. The jet stream, combined with a tropospheric fold, resulted in explosive deepening of the low. As the low moved through…

3. Feb 24, 2007Winter Storm, Hancock$250,000
   National Weather Service narrative

   A major winter storm affected Iowa through the 24th and 25th of February. A powerful upper low moved onto the west coast during the middle of the week, and advanced east through the Rockies during the end of the week. Strong warm air advection took place over the top of a shallow polar airmass that was in place over Iowa. The east-southeasterly flow at the surface drew cool and dry air into the state from the east, setting the stage for a significant ice storm. The main area of precipitation overspread the state during the early morning hours of the 24th and persisted through much of the 25th. Initially, very warm air aloft meant that the precipitation fell in the form of freezing…

4. Jun 23, 1998Thunderstorm Wind$200,000
   National Weather Service narrative

   Once again, a warm frontal boundary was located to the south of Iowa with very warm and unstable air just to the south of the front. Dew point temperatures were in the low 70s in the warm air. This moisture was drawn north over the frontal boundary, into Iowa. A large mesoscale convective system developed over northwest Iowa and moved east during the evening hours. Initially, the system produced hail over an inch in diameter, but the main severe weather associated with the storms was high winds. Some building damage was reported in Palmer in Pocahontas County. A grain bin was damaged by high winds in Humboldt in Humboldt County. Windows were blown out at a mall department store in…

5. May 16, 1999Flood, Hancock$200,000
   National Weather Service narrative

   May of 1999 saw several significant flooding episodes across the Des Moines CWA. For the most part, central Iowa was spared the extremely heavy rainfall that caused major, and at several locations record, flooding along rivers in the northeast and east parts of the state. The most serious flooding was caused by heavy rains during the overnight hours of May 16. The heaviest rains fell in the counties just to the northeast of the Des Moines CWA. Up to 8 inches of rain fell over parts of Fayette County with anywhere from 2 to 6 inches falling over parts of Butler, Bremer, and Black Hawk Counties. Most of the rain fell in the Cedar River basin, which includes the West Fork Cedar…

6. Jun 16, 2014Thunderstorm Wind$150,000
   National Weather Service narrative

   Machine shed completely destroyed. Damage to power lines and trees.

7. Jul 10, 2017Thunderstorm Wind$150,000
   National Weather Service narrative

   Storm chaser video depicted extensive wind damage and likely wind driven hail damage in the town of Klemme. Damage included numerous car, home, and business windows broken and trees downed on homes. This is a delayed report and time estimated from radar.

8. Apr 7, 2001Flood, Hancock$150,000
   National Weather Service narrative

   The first significant rainfall of the month affected much of the Des Moines Hydrologic Service Area (HSA) on the 5th as scattered showers and the seasons's first thunderstorms moved across the area. The 24-hour isohyetal map showed a chaotic pattern as 0.50 to 0.75 inches fell across west central Iowa, mainly in the North Raccoon River basin. Rains in excess of a half-inch fell along the southern border of Iowa. Less than 0.10 of an inch fell over northwest and south central parts of the HSA, while a broad area of around 0.25 inches fell from just north of Des Moines northeast into the Cedar basin. Early on the 6th a few severe storms developed over west central Iowa and moved…

9. Jul 15, 2011Excessive Heat, Hancock$135,000
   National Weather Service narrative

   A large area of high pressure developed in the upper atmosphere by the middle of July. Heat built up over Iowa, aided by the severe drought to the south across Kansas, Oklahoma, and Texas. Temperatures rose into the 90s each day through the period. Though most days did not see 100 degree heat, the dewpoint and overnight lows were very significant. Low temperatures during most of the nights were in the 70s, with many of the nights in the mid to upper 70s. Dewpoint temperatures failed to fall below 70 through most of the period, with frequent excursions in the upper 70s to low 80s. These conditions caused considerable stress on livestock. Reports indicated that at least 4000 head of…

10. Aug 26, 2004Hail$100,000
    National Weather Service narrative

    A very unstable airmass was located over Iowa on the 26th. Surface dew points rose into the mid to upper 70s along with surface temperatures near 90. Soundings indicated CAPE values around 5000 J/kg with lifted indices in the -9 C. range. The freezing level was relatively low, being a little over 12,000 feet. A steep lapse rate was in place with a 7 to 8 C. lapse rate between 850 and 500 mb. At the same time, a strong west to southwest jet in excess of 75 kts was in place over the central U.S. During the afternoon, a cold front dropped southeast into the state. Thunderstorms erupted during the late afternoon in advance of the cold front. The storms became severe very quickly and…

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

104°FJul 7, 1980

All-time low

−32°FFeb 2, 1996

Warmest night

79°FJul 10, 1976

Coldest day

−20°FDec 23, 1983

Wettest day

6.33 inAug 22, 1954

Snowiest day

12.4 inMar 24, 2018

Hottest year

2012mean 49.9°F

Coldest year

1950mean 41.6°F

Wettest year

201850.01 in

Driest year

195814.79 in

Snowiest season

68.5 in1970-71

Station Mason City Municipal Airport (USW00014940), 1,188 ft elevation, 19.5 miles from the population centre. Daily records from 1948 to October 26, 2026; 99.9% 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 USW00014940.
• 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.