NHC HURDAT2 · SPC Tornado Database
Hurricanes and Tornadoes That Hit Mason City, 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 Mason City, Iowa since records began in 1851. Since 1950, 114 tornadoes have touched down within 25 miles, 12 of them rated EF3 or stronger.
- Hurricanes
- 0
- Tropical storms
- 0
- Tornadoes
- 114
- EF3 or stronger
- 12
within 75 mi, since 1851
below hurricane strength
within 25 mi, since 1950
20 deaths in all
What the records show for Mason City
The highest rating among the 114 tornadoes within 25 miles is F5, reached 2 times; the most recent, on May 15, 1968, came within 20 miles. Of the 114, 13 had paths within 5 miles of the city centre, and 50 have come since 2000. June has had the most tornadoes, 28. The most recent tornado was on July 28, 2025. Of the 241 Iowa cities on this site, 66% have more tornadoes within 25 miles than Mason City. Hail has been reported within 10 miles 139 times since 1959, with stones up to 3 inches (tea cup size). Mason City has more hail reports within 10 miles than 77% of the 241 Iowa cities.
Compare Mason City's storm record with another city →
Tornadoes within 25 miles of Mason City
By decade
- 2020s23
- 2010s10
- 2000s17
- 1990s22(1 EF3+)
- 1980s13
- 1970s9(2 EF3+)
- 1960s14(7 EF3+)
- 1950s6(2 EF3+)
| Date | Rating | Distance | Path | Killed / injured |
|---|---|---|---|---|
| May 15, 1968 | F5 | 20 mi | 62.1 mi | 13 / 462 |
| Oct 14, 1966 | F5 | 23 mi | 9.7 mi | 6 / 172 |
| Apr 30, 1967 | F4 | 21 mi | 7.6 mi | 0 / 1 |
| Apr 30, 1967 | F4 | 10 mi | 13.3 mi | 0 / 0 |
| May 5, 1965 | F4 | 21 mi | 41.6 mi | 0 / 11 |
| May 10, 1953 | F4 | 14 mi | 26.6 mi | 0 / 3 |
| May 20, 1953 | F3 | 23 mi | 116.1 mi | 1 / 0 |
| Jun 18, 1994 | F3 | 21 mi | 6 mi | 0 / 0 |
| May 28, 1974 | F3 | 12 mi | 3.8 mi | 0 / 3 |
| Jul 12, 1971 | F3 | 15 mi | 15.4 mi | 0 / 0 |
| Apr 30, 1967 | F3 | 12 mi | 17.2 mi | 0 / 0 |
| Apr 30, 1967 | F3 | 5 mi | 7.7 mi | 0 / 0 |
The strongest 12 of 114, by rating and then by deaths. Ratings before February 2007 are on the original Fujita scale.
Hail in Mason City
The Storm Prediction Center has 139 hail reports within 10 miles of Mason City since 1959, made on 77 separate days. Of these, 88 were 1 inch across or larger, and one reached 2 inches. The largest, 3 inches (tea cup size), fell on June 18, 1974. The most recent report is from June 20, 2025. June has the most reports, 37.
Source: NOAA Storm Prediction Center severe weather reports, data through 2025.
Weather by month in Mason City
The nearest NOAA station with 1991–2020 climate normals is Mason City, IA, in Mason City at 1,105 feet. July is the warmest, with an average high of 82°F and low of 62°F; January is the coolest, at 24°F and 7°F. June is the wettest at 5.7 inches of precipitation on average and January the driest at 0.9 inches; the year adds up to 36.4 inches over 64 days with at least a tenth of an inch. Highs reach 90°F on about 9 days a year, almost all from June to August. Lows fall below freezing on about 161 nights a year. That 36.4 inches is more than at 51 of the 124 Iowa stations used on this site (41%). Clear Lake, 9 miles west, has its own station (Mason City Municipal Airport, IA): 36.4 inches a year, the same as here, and a July average high of 83°F against 82°F.
| Month | High °F | Low °F | Precip. in | Days ≥ 0.1" |
|---|---|---|---|---|
| Jan | 24 | 7 | 0.9 | 3 |
| Feb | 29 | 11 | 1.1 | 3 |
| Mar | 41 | 23 | 2.0 | 4 |
| Apr | 56 | 35 | 3.9 | 7 |
| May | 69 | 47 | 5.6 | 9 |
| Jun | 79 | 58 | 5.7 | 9 |
| Jul | 82 | 62 | 4.6 | 7 |
| Aug | 80 | 59 | 3.7 | 6 |
| Sep | 74 | 50 | 3.2 | 5 |
| Oct | 60 | 38 | 2.6 | 5 |
| Nov | 43 | 25 | 1.8 | 3 |
| Dec | 30 | 14 | 1.3 | 3 |
| Year | 55 | 36 | 36.4 | 64 |
Averages for 1991–2020 at Mason City, IA (1,105 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 Mason City
Since 1996, the National Weather Service has logged 248 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Mason City: 135 thunderstorm wind reports, 64 heavy rain events, 29 flash floods, 16 floods and 4 lightning strikes. They killed 0 people and injured 7, and the NWS estimated $6.7 million in property and crop damage. The strongest thunderstorm gust on record here was 83 mph, on December 15, 2021. June has had the most flash floods, 16 of 29. Of the 240 Iowa cities on this site with a flash flood on record, 195 have had fewer than Mason City.
June 15, 1997: thunderstorm wind 9 miles from the centre of Mason City — 4 injured, $40,000 damage.
August 4, 1996: thunderstorm wind in Mason City — 1 injured, $25,000 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 Mason City's ZIP code 50401 have filed 202 claims with the National Flood Insurance Program since 1978, and were paid $3.0 million for buildings and contents, in the dollars of each year. The most came from Storm in 2008: 85 claims (42% of all) and $2.6 million, then Flooding in 1984 with 13. 49% 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, 75 have fewer than Mason City.
| Event | Claims | Paid |
|---|---|---|
| Storm2008 | 85 | $2.6 million |
| Flooding1984 | 13 | $65,000 |
Cerro Gordo County, which includes Mason City, has been named in 15 federal disaster or emergency declarations since 1965, 13 of them major disasters (by incident: 6 floods, 4 severe storms, 2 biological emergencies, 1 hurricane). The latest major disaster declaration was Covid-19 Pandemic, on March 23, 2020. FEMA's National Risk Index gives Cerro Gordo County a Relatively Low rating for natural hazard risk overall; by hazard: Relatively Moderate for tornadoes, hail and strong wind; Relatively Low for inland flooding; Very Low for hurricanes, lightning and heat waves. It models the county's expected loss from all 18 hazards it covers at $27.4 million a year, the 12th highest of 99 Iowa counties; of the hazards above, the largest share, $12.1 million (44%), 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.