NHC HURDAT2 · SPC Tornado Database
Hurricanes and Tornadoes That Hit Rock Valley, IA
Every tropical system within 75 miles since 1851 and every tornado within 25 miles since 1950.
Data: NOAA NHC HURDAT2 and NOAA SPC tornado and hail reports, through 2025 · Updated
No tropical storm or hurricane has passed within 75 miles of Rock Valley, Iowa since records began in 1851. Since 1950, 141 tornadoes have touched down within 25 miles, 5 of them rated EF3 or stronger.
- Hurricanes
- 0
- Tropical storms
- 0
- Tornadoes
- 141
- EF3 or stronger
- 5
within 75 mi, since 1851
below hurricane strength
within 25 mi, since 1950
3 deaths in all
What the records show for Rock Valley
The highest rating among the 141 tornadoes within 25 miles is F3, reached 5 times; the most recent, on July 5, 1978, came within 7 miles. The deadliest, an F2 on April 26, 1986, killed 1 person. Of the 141, 2 had paths within 5 miles of the city centre, and 62 have come since 2000. June has had the most tornadoes, 37. The most recent tornado was on July 28, 2025. Rock Valley has more tornadoes within 25 miles than 66% of the 241 Iowa cities on this site. Hail has been reported within 10 miles 114 times since 1978, with stones up to 2.75 inches (baseball size). Rock Valley has more hail reports within 10 miles than 66% of the 241 Iowa cities.
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Tornadoes within 25 miles of Rock Valley
By decade
- 2020s13
- 2010s18
- 2000s31
- 1990s30
- 1980s14
- 1970s14(2 EF3+)
- 1960s15(3 EF3+)
- 1950s6
| Date | Rating | Distance | Path | Killed / injured |
|---|---|---|---|---|
| Jul 5, 1978 | F3 | 7 mi | 8 mi | 0 / 0 |
| May 31, 1971 | F3 | 19 mi | 46.5 mi | 0 / 0 |
| Sep 22, 1968 | F3 | 18 mi | 4.7 mi | 0 / 0 |
| Jun 14, 1967 | F3 | 24 mi | 6.2 mi | 0 / 3 |
| Jun 7, 1965 | F3 | 22 mi | 11.5 mi | 0 / 0 |
| Apr 26, 1986 | F2 | 21 mi | 18.5 mi | 1 / 4 |
| Jul 14, 1970 | F2 | 21 mi | 3.8 mi | 1 / 1 |
| May 1, 2008 | EF2 | in town | 12.95 mi | 0 / 0 |
| Jun 7, 1993 | F2 | 24 mi | 10 mi | 0 / 5 |
| May 7, 1993 | F2 | 21 mi | 11.5 mi | 0 / 0 |
| May 7, 1993 | F2 | 22 mi | 15 mi | 0 / 0 |
| May 7, 1993 | F2 | 22 mi | 15 mi | 0 / 1 |
The strongest 12 of 141, by rating and then by deaths. Ratings before February 2007 are on the original Fujita scale.
Hail in Rock Valley
The Storm Prediction Center has 114 hail reports within 10 miles of Rock Valley since 1978, made on 61 separate days. Of these, 84 were 1 inch across or larger, and 5 reached 2 inches. The largest size, 2.75 inches (baseball size), was reported on 2 days, most recently September 3, 1980. The most recent report is from September 21, 2025. June has the most reports, 39.
Source: NOAA Storm Prediction Center severe weather reports, data through 2025.
Weather by month in Rock Valley
The nearest NOAA station with 1991–2020 climate normals is Sioux Ctr 2 SE, IA, 13 miles southeast of Rock Valley at 1,360 feet. July is the warmest, with an average high of 85°F and low of 62°F; January is the coolest, at 27°F and 9°F. June is the wettest at 4.5 inches of precipitation on average and January the driest at 0.7 inches; the year adds up to 30.0 inches over 57 days with at least a tenth of an inch. Highs reach 90°F on about 23 days a year, almost all from May to September. Lows fall below freezing on about 155 nights a year. Snowfall averages 34.8 inches a year, most of it in February. That 30.0 inches is more than at 6 of the 124 Iowa stations used on this site (5%). Hawarden, 15 miles southwest, has its own station (Hawarden, IA): 30.0 inches a year, the same as here, and the same July average high, 85°F.
| Month | High °F | Low °F | Precip. in | Days ≥ 0.1" | Snow in |
|---|---|---|---|---|---|
| Jan | 27 | 9 | 0.7 | 2 | 6.8 |
| Feb | 33 | 14 | 0.9 | 3 | 7.7 |
| Mar | 46 | 25 | 1.7 | 4 | 5.6 |
| Apr | 61 | 36 | 3.0 | 6 | 3.1 |
| May | 73 | 48 | 4.2 | 8 | 0.1 |
| Jun | 82 | 59 | 4.5 | 7 | 0.0 |
| Jul | 85 | 62 | 3.5 | 5 | 0.0 |
| Aug | 82 | 60 | 3.4 | 6 | 0.0 |
| Sep | 77 | 51 | 3.2 | 5 | 0.0 |
| Oct | 64 | 39 | 2.5 | 5 | 0.9 |
| Nov | 46 | 25 | 1.4 | 3 | 3.9 |
| Dec | 32 | 15 | 1.0 | 3 | 6.7 |
| Year | 59 | 37 | 30.0 | 57 | 34.8 |
Averages for 1991–2020 at Sioux Ctr 2 SE, IA (1,360 ft), from NOAA NCEI U.S. Climate Normals. Normals describe the station; the farther a place is from it, and the bigger the difference in height, the more its weather can differ.
Floods, thunderstorm wind and lightning near Rock Valley
Since 1996, the National Weather Service has logged 113 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Rock Valley: 63 thunderstorm wind reports, 31 floods and 19 flash floods. None is recorded as killing or injuring anyone; the NWS estimated $4.3 million in property and crop damage. The strongest thunderstorm gust on record here was 96 mph, on July 28, 2025. June has had the most flash floods, 10 of 19. Of the 240 Iowa cities on this site with a flash flood on record, 164 have had fewer than Rock Valley.
August 5, 2023: flash flood 10 miles from the centre of Rock Valley — $1.5 million damage.
June 15, 2014: flood 6 miles from the centre of Rock Valley — $1.0 million damage.
NWS: “Repeated heavy rains caused record flooding of the Big Sioux River. Farmland and other lowlands including numerous roads were flooded, especially along the river in southwestern Sioux County, near and south of where the flooding Rock River empties into the Big Sioux.”
June 16, 2014: flood 10 miles from the centre of Rock Valley — $1.0 million damage.
Source: NOAA NCEI Storm Events Database, events whose starting point is on record, 1996 to June 30, 2026. Damage is the NWS estimate in the dollars of the year, not insured losses, and NWS notes that some reports are unverified.
Flood insurance claims, disaster declarations and FEMA risk ratings
Flood insurance policyholders in Rock Valley's ZIP code 51247 have filed 19 claims with the National Flood Insurance Program since 2010, and were paid $1.5 million for buildings and contents, in the dollars of each year. The year with the most claims was 2024, with 10. 53% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 91 Iowa cities on this site with 10 or more claims, 23 have fewer than Rock Valley.
Sioux County, which includes Rock Valley, has been named in 15 federal disaster or emergency declarations since 1965, 12 of them major disasters (by incident: 6 severe storms, 5 floods, 2 biological emergencies, 1 drought). The latest major disaster declaration was Severe Storms, Flooding, Straight-Line Winds, and Tornadoes, on June 24, 2024. FEMA's National Risk Index gives Sioux County a Relatively Low rating for natural hazard risk overall; by hazard: Relatively High for hail; Relatively Moderate for tornadoes; Relatively Low for inland flooding, strong wind, lightning and heat waves. It models the county's expected loss from all 18 hazards it covers at $29.8 million a year, the 11th highest of 99 Iowa counties; of the hazards above, the largest share, $11.4 million (38%), is from inland flooding.
Claims: FEMA, OpenFEMA Dataset FIMA NFIP Redacted Claims – v3, summed over ZIP codes; payments in the dollars of each year, not adjusted for inflation. Declarations: Disaster Declarations Summaries – v2, by county. Retrieved October 25, 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).
Risk ratings: FEMA, National Risk Index county table, December 2025 (v1.20), retrieved October 26, 2026; ratings compare counties nationwide, are meant for planning and are no substitute for a local risk assessment. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets 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).
What counts as a pass, the distances and the sources: how this storm history is built.
Cities near Rock Valley
- Hull, IA9 mi
- Sioux Center, IA11 mi
- Hawarden, IA15 mi
- Canton, SD16 mi
- Orange City, IA18 mi
- Rock Rapids, IA18 mi
- Larchwood, IA19 mi
- Sheldon, IA23 mi
- Harrisburg, SD24 mi
- Beresford, SD25 mi
- Akron, IA27 mi
- Le Mars, IA28 mi
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