| June 2014 | Flood | Alcester | $1,000,000 | Repeated heavy rains caused record flooding of the Big Sioux River. Farmland and other lowlands including numerous roads were flooded. Some roads were damaged, and some secondary roads were washed out. A few farm homes, other farm buildings, and some fences were damaged by floodwaters. The river crested at a record 12.92 feet above flood stage at Hawarden, Iowa on June 17th. Interstate 29 was temporarily closed along a 22 mile stretch to facilitate levee building to divert some Big Sioux River water to McCook Lake, but the Interstate was re-opened when the river crested at a lower level than was feared. A levee breach across the river from Akron, Iowa, briefly aggravated lowland flooding before it was repaired. |
| September 2010 | Flood | Alcester | $100,000 | Widespread heavy rain, combined with saturated ground, caused a fairly rapid rise of the Big Sioux River to moderate to major flooding levels. Roads and numerous agricultural land near the river were flooded, as well as a few homes. A dike break just south of Big Springs caused additional farmland to be flooded. The river crested at 6.9 feet above flood stage near Akron, Iowa on September 27th. |
| July 2003 | Thunderstorm Wind | Alcester | $100,000 | Thunderstorm winds caused widespread tree damage and blew down power lines. Several homes and other buildings in Alcester were damaged, mostly by falling trees or tree debris. The downed and damaged power lines caused power outages. |
| July 1999 | Thunderstorm Wind | Alcester | $50,000 | no account filed |
| September 2019 | Flood | Alcester | $25,000 | After excessive two-day rainfall during September 10-12 (7.81 inches at Dell Rapids, generally 3 to 4 inches around Sioux Falls, 4.72 inches at Canton), the Big Sioux River above Hawarden (gage site HWDI4) reached the third highest stage on record of 12.33 feet above flood stage on September 15. Significant amounts of the agricultural flood plain were inundated, and numerous roads were closed including South Dakota Highway 46, Iowa Highway 10 and South Dakota county road 13. |
| October 2019 | Flood | Alcester | $5,000 | Rainfall which averaged 1.00 to 1.50 inches around Sioux Falls and from 2.00 to 3.00 inches along the Rock River Basin in northwest Iowa at the start of the month pushed the Big Sioux River above Hawarden (gage site HWDI4) into minor flooding. The river crested 1.52 feet above flood stage on October 6. Extensive agricultural flooding occurred. Property damage costs are rough estimates. |
| April 2004 | Thunderstorm Wind | Alcester | $5,000 | Thunderstorm winds caused tree damage, including two forty foot pine trees blown down. The winds also blew down power lines, causing a local power outage. |
| June 2020 | Thunderstorm Wind | Alcester | $3,000 | Shingles were dislodged from a house and tossed into the driveway. Property damage costs are rough estimates. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture. |
| June 2020 | Thunderstorm Wind | Alcester | $1,000 | Numerous branches of 3 to 6 inches diameter were broken from trees. Property damage costs are rough estimates. |
| June 2005 | Hail | Alcester | $1,000 | Wind driven large hail broke windows on one side of a house. |
| July 2025 | Thunderstorm Wind | Alcester | - | Thunderstorm winds caused significant tree and powerline damage throughout Alcester. |
| July 2024 | Flood | Alcester | - | Flooding continued from June on the Big Sioux River near Hawarden, with declining river levels. The river fell below flood stage on the morning of July 5th. |
| July 2024 | Thunderstorm Wind | Alcester | - | Thunderstorm winds downed a large tree in Alcester. |
| June 2024 | Flood | Alcester | - | The Big Sioux River above Hawarden rose above flood stage the evening of June 20th, cresting around 19.42 feet above flood stage (39.92 feet) on June 22nd. This crest is in the Major Stage and broke the previous record. The river stayed above flood stage into July. For a more comprehensive description of flood damage, please see other entries for Union County. |
| April 2023 | Flood | Alcester | - | The Big Sioux River near Hawarden, IA rose above flood stage on the morning of April 10th before cresting around 2.39 feet above flood stage (22.89 feet) on April 13th. The river then fell below flood stage on the morning of April 16th. |
| March 2020 | Flood | Alcester | - | The Big Sioux River above Hawarden (gage site HWDI4) crested 0.35 feet above flood stage on March 10. Minor flooding of agricultural land occurred near the river. |
| June 2020 | Thunderstorm Wind | Alcester | - | Wind gust to 58 mph was measured by a personal weather station. |
| March 2020 | Flood | Alcester | - | With rainfall of 1.58 inches at Rock Valley, 1.51 inches at Canton and an average of 1.00 to 1.50 inches around Sioux Falls, the Big Sioux River above Hawarden (gage site HWDI4) returned to flood at the end of the month. The river crested at 2.52 feet above flood stage on March 30, resulting in significant flooding of crop and pasture land. The river remained at minor flood stage at the end of the month. |
| April 2020 | Flood | Alcester | - | A continuation of minor flooding from March, the Big Sioux River above Hawarden (gage site HWDI4) began the month 1.59 feet above flood stage, with a steady and slow drop at the start of the month to below flood stage on April 4. Impacts continued with significant flooding of crop and pasture land. |
| June 2019 | Flood | Alcester | - | The Big Sioux River above Hawarden (gage site HWDI4) crested 3.46 feet above flood stage on June 28, causing significant flooding of crop and pasture land. The river remained in minor flood stage at the end of the month. |
| June 2019 | Flood | Alcester | - | A continuation of flooding from May, the Big Sioux River above Hawarden (gage site HWDI4) began the month at 8.68 feet above flood stage. Significant amounts of agricultural land remained flooded, and further impeded spring planting. |
| March 2019 | Flood | Alcester | - | Snow melt and heavy rainfall (measured 2.12 inches at Hawarden and 1.75 inches at Canton) resulted in extensive flooding of agricultural land in the flood plain. Iowa Highway 10 and South Dakota Highway 46 were both inundated by water, along with access from County Road 13 west of Hawarden. The Big Sioux River above Hawarden (gage site HWDI4) reached the highest crest on record at 14.8 feet above flood stage on March 15. The river remained in moderate flood stage at the end of the month. |
| July 2019 | Flood | Alcester | - | The Big Sioux River above Hawarden (gage site HWDI4) crested 2.99 feet above flood stage on July 6. After less than 24 hours below flood stage during July 14-15, a secondary crest of 3.92 feet above flood stage occurred on July 19, resulting in significant flooding of crop and pasture land. |
| May 2019 | Flood | Alcester | - | This is a continuation of flooding from April. The Big Sioux River above Hawarden (gage site HWDI4) remained in flood through the month. Late month rains pushed the river to a crest at 10.33 feet above flood stage on May 29, the third highest stage on record. Significant agricultural flooding persisted, with no opportunity for spring planting throughout the flood plain. County road 13, Iowa Highway 10 and South Dakota Highway 46 were again subjected to closure at the end of the month. The river remained at major flood stage at the end of the month. |
| April 2019 | Flood | Alcester | - | Runoff from occasional precipitation in late March and April maintained significant flooding of agricultural and pasture lands near the Big Sioux River. The Big Sioux River above Hawarden (gage site HWDI4) crested at 7.19 feet above flood stage on April 9. Moderate flooding continued at the end of the month. |
| April 2018 | Flood | Alcester | - | Snow melt and runoff from periods of heavier rainfall produced moderate flooding which produced significant impact to lowland agricultural areas, and inundated SD Highway 46 for several days. River levels reached 5.9 feet above flood stage above Hawarden (gage site HWDI4) on April 24. The river remained at minor flood stage at the end of the month. |
| April 2018 | Flood | Alcester | - | A continuation of flooding from March 2018, the river above Hawarden (gage site HWDI4) slowly fell to below flood stage by April 5. |
| June 2018 | Flood | Alcester | - | A week of periodic heavy rainfall ending June 26 resulted in a widespread 5 to 9 inches of rainfall, much of which occurred on June 20, 24 and 25. Specific weekly totals included 6.28 inches near Larchwood, 7.47 inches at Canton, 9.15 inches at Rock Valley, 9.19 inches near Lester and 5.01 inches at Hawarden. Major flooding occurred with South Dakota Highway 46 and Iowa Highway 10 going under water, as well as the city park in Hawarden. Significant amounts of crop and pasture land were inundated as the river crested above Hawarden (gage site HWDS2) 13.5 feet above flood stage on June 22. After falling, a second crest 10.8 feet above flood stage occurred on June 27. The river remained at minor flood stage at months end. |
| September 2018 | Flash Flood | Alcester | - | Fields flooded from heavy rainfall. Water onto several gravel roads. |
| March 2018 | Flood | Alcester | - | Heavy rainfall along with snow melt caused minor flooding of lowland agricultural areas along middle portions of the Big Sioux River. The river reached a crest of 1.7 feet above flood stage near Hawarden (gage site HWDI4) on March 7. |
| March 2018 | Flood | Alcester | - | Runoff from rainfall, snow melt, and ice breakup caused minor flooding of lowland agricultural areas along lower portions of the Big Sioux River. The river reached a crest of 4.2 feet above flood stage near Hawarden (gage site HWDI4) on March 30, and remained above flood stage at the end of the month. |
| July 2018 | Flood | Alcester | - | South Dakota Highway 46 was closed for several days to start July, and crop and pasture land near the Big Sioux River was severely impacted as river levels climbed to 3.7 feet above flood stage above Hawarden (gage site HWDI4) on July 7. |
| September 2018 | Flood | Alcester | - | Widespread upstream rainfall in the Big Sioux basin from September 18-20 totaled generally 5 to 10 inches, resulting in major flooding. South Dakota Highway 46 was closed, with several farm houses isolated by high water as the Big Sioux River above Hawarden (gage site HWDI4) crested 11.1 feet above flood stage on September 22. |
| June 2018 | Thunderstorm Wind | Alcester | - | At the corner of State Highway 11 and 300th St., thunderstorm winds leveled a seed warehouse and office. The debris was spread across the highway into an abandoned building across the street. At the latter location, winds blew over a refrigerated semi-trailer. |
| October 2018 | Flood | Alcester | - | A steady moderate rainfall during October 9-10 - resulting in 1.50 to 2.00 inches of rainfall - produced yet another period of moderate flooding. South Dakota Highway 46 was again inundated, and several rural homes were isolated by high water. The Big Sioux River above Hawarden (gage site HWDI4) crested 4.6 feet above flood stage on October 12. |
| May 2018 | Flood | Alcester | - | A slow fall through minor flood stages persisted along much of the Big Sioux River during much of the first week of May, with impacts generally limited to flooding of agricultural areas near the river. Flooding ended above Hawarden (gage site HWDI4) on May 5. |
| May 2018 | Flood | Alcester | - | Runoff from periods of heavier rainfall on top of already high river levels produced minor flooding of lowland agricultural areas along lower portions of the Big Sioux River. River levels reached 2.8 feet above flood stage above Hawarden (gage site HWDI4) on May 13. |
| June 2017 | Thunderstorm Wind | Alcester | - | Social Media report. |
| April 2016 | Flood | Alcester | - | Runoff from repeated rains caused minor flooding of agricultural land along the Big Sioux River. The river reached a peak stage 1.6 feet above flood stage at Akron on the Iowa side of the river at the end of the month. |
| May 2016 | Flood | Alcester | - | Minor flooding because of runoff from repeated April rains continued to affect agricultural land along the Big Sioux River. The river crested at 2.2 feet above flood stage at Akron on the Iowa side of the river on May 3rd. |
| August 2015 | Thunderstorm Wind | Alcester | - | Thunderstorm winds cause tree damage, including trees snapped off. |
| July 2015 | Thunderstorm Wind | Alcester | - | Thunderstorm winds caused tree damage, including up to 6 inch diameter limbs blown down. |
| May 2013 | Flood | Alcester | - | Minor to briefly major flooding of the Big Sioux River affected a significant amount of farmland, with other lowlands and several roads also being flooded. The river crested at 4.47 feet above flood stage east of Spink on May 28th. |
| May 2012 | Flood | Alcester | - | Minor to moderate flooding of the lower Big Sioux River affected some farmland and roads. The river crested at 2.2 feet above flood stage at Hawarden, Iowa on May 31st, and at 2.26 feet above flood stage at Akron, Iowa, also on May 31st. |
| May 2012 | Flood | Alcester | - | Minor to moderate flooding of the Big Sioux River affected some farmland, parkland, and a few roads. The river crested at 2.2 feet above flood stage at Hawarden, Iowa on May 10th, and at 2.31 feet above flood stage at Akron, Iowa on May 11th. |
| May 2011 | Flood | Alcester | - | Heavy rain caused the lower Big Sioux River to rise again above flood stage, after spring snowmelt flooding subsided. Minor to moderate flooding was reported with some farmland and a few roads flooded. The river crested at close to 2 feet above flood stage across the river at Hawarden and Akron, Iowa, then began to fall again by the end of the month. |
| June 2011 | Flood | Alcester | - | Minor to moderate flooding continued on the lower Big Sioux River in June, with lowlands including some farmland and several roads flooded. The river fell below flood stage for a few days in the middle of June, rose again due to heavy rains, and began to fall again before the end of the month. The river crested at 3.3 feet above flood stage at Akron, Iowa on June 25th, and at 3.6 feet above flood stage at Hawarden, Iowa on June 24th. |
| February 2011 | Flood | Alcester | - | A few days of melting snow in mild weather caused minor flooding along the Big Sioux River, affecting lowlands including farmland and pastureland on the South Dakota side of the river. The river crested at 1.3 feet above flood stage across from Hawarden, Iowa on February 21st. |
| July 2011 | Flood | Alcester | - | Moderate to major flooding redeveloped along the Big Sioux River, then subsided during the month. Lowlands along the river were flooded, including farmland and several roads. The highest stages were 5.0 feet above flood stage at the Hawarden, Iowa gage, and 4.0 feet above flood stage at Akron, Iowa, both on July 18th. |
| April 2010 | Flood | Alcester | - | Continued flooding of the Big Sioux River from March abated and ended in early April, with minor flooding affecting mainly fields adjacent to the river. Starting the month at near a foot above flood stage several miles northeast of Richland, the river fell below flood stage on April 4th. |
| June 2010 | Flood | Alcester | - | Recurring heavy rain cause moderate flooding of the Big Sioux River. Some roads and fields along the river were flooded. The river crested at just over 3 feet above flood stage near Akron, Iowa, or several miles northeast of Richland, South Dakota, on June 23rd. |
| October 2010 | Flood | Alcester | - | Minor to moderate flooding of the Big Sioux River steadily abated and ended during the first few days of the month. Some roads and riverside lowlands including agricultural land were still flooded at the start of the month. |
| July 2010 | Flood | Alcester | - | Runoff from heavy rain caused minor to moderate flooding along the Big Sioux River. Farmland and other lowlands were flooded. The river rose to over 4 feet above flood stage near Akron, Iowa at the end of the month and was still rising. |
| August 2010 | Flood | Alcester | - | Minor to moderate flooding along the Big Sioux River continued at the start of August after late July heavy rains, but the flooding abated after a few days. Farmland and other lowlands were flooded. The highest level near Akron, Iowa was 4.54 feet above flood stage on August 1st. |
| March 2010 | Flood | Alcester | - | Rapid melting of a heavy winter snowpack caused flooding of the Big Sioux River which resulted in moderate to major flooding. Several fields and roads were flooded. The river crested at 6.4 feet above flood stage several miles northeast of Richland on March 17th. A damaged dike near this location caused more widespread flooding of cropland, and also resulted in the flooding and closing of South Dakota Highway 48 in the area. |
| February 2009 | Flood | Alcester | - | Minor flooding along the Big Sioux River resulted from the melting of snow. Some farmland and a few county roads were partially flooded. |
| June 2008 | Flood | Alcester | - | Heavy rain caused moderate to major flooding of the Big Sioux River. Extensive flooding of farmland and flooding of several county roads was reported. The amout of damage to crops and to farmland from erosion was not known. |
| April 2007 | Flood | Alcester | - | Heavy rain at the end of March led to minor to locally moderate flooding along the Big Sioux River. Lowlands including some farmland near the river were flooded. |
| September 2007 | Hail | Alcester | - | Large hail was accompanied by 40 to 50 mph wind gusts. |
| March 2007 | Flood | Alcester | - | Warm temperatures caused a rapid snowmelt which caused the Big Sioux River to rise above flood stage for several days. The flooding varied from minor to major with lowlands near the river flooded. The amount of damage was not known but was not suspected to be large. The river crested at 7.7 feet above flood stage east of Alcester on March 16th.| |
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