Storm risk in Story County, Iowa

FEMA's overall hazard score for Story County is 68.83 (Relatively Low), 981st of 3,144 counties. Hail scores 86.83 (Relatively Moderate), strong wind 69.88 (Relatively Moderate) and tornado 91.35 (Relatively High). Expected hail loss is $21 per $1 million of buildings a year; NOAA logged 153 hail reports in Story County from 2014 to June 2026.

FEMA National Risk Index, version December 2025, retrieved October 8, 2026. NOAA hail reports 2014 to June 2026.

Story County: expected yearly loss per $1 million of buildings for hail, strong wind and tornado, on a log scale, against all U.S. counties and the counties of IA$0.1$1$10$100$1,000Hail: $21 per $1 million, 1,605th of 3,126 rated counties$21Hail1,605th of 3,126 countiesStrong wind: $25 per $1 million, 1,364th of 3,121 rated counties$25Strong wind1,364th of 3,121 countiesTornado: $466 per $1 million, 491st of 3,144 rated counties$466Tornado491st of 3,144 counties
  • Story County, coloured by its FEMA rating
  • all U.S. counties
  • each county in the state
  • U.S. median
  • state median

Expected yearly loss per $1 million of buildings, log scale. Dot colour is FEMA’s rating band. The tornado lane counts everything exposed, not only buildings.

How FEMA rates Story County

HazardRatingScore (0 to 100)Rank in U.S.Rank in IA
OverallRelatively Low 68.83981 of 3,1449 of 99
HailRelatively Moderate 86.83415 of 3,12622 of 99
Strong windRelatively Moderate 69.88948 of 3,12632 of 99
TornadoRelatively High 91.35273 of 3,1268 of 99

Expected yearly loss, in dollars

HazardThis county, total a yearPer $1M of buildingsState median countyU.S. median countyRank per $1M, U.S.Rank per $1M, state
Hail$470,689$21 $51$22 1,605 of 3,12690 of 99
Strong wind$550,631$25 $66$20 1,364 of 3,12195 of 99
Tornado$10,363,004$466 $417$199 491 of 3,14437 of 99

Rank 1 is the highest. Overall, hail and wind losses count buildings; the tornado row counts everything FEMA exposes, so it overstates building damage. Expected annual loss is an average over many years for the whole county, not a forecast for one roof.

What stands out in Story County

  • FEMA expects hail in Story County to cost $21 per $1 million of buildings a year: 0.95 times the U.S. median and 0.41 times the IA county median, ranked 1,605th of 3,126 counties nationally and 90th of 99 in Iowa.
  • FEMA expects strong wind in Story County to cost $25 per $1 million of buildings a year: 1.21 times the U.S. median and 0.37 times the IA county median, ranked 1,364th of 3,121 counties nationally and 95th of 99 in Iowa.
  • FEMA expects tornado in Story County to cost $466 per $1 million of buildings a year: 2.34 times the U.S. median and 1.12 times the IA county median, ranked 491st of 3,144 counties nationally and 37th of 99 in Iowa.
  • Applying FEMA's estimate to a $243,600 home, the average yearly loss in Story County is about $5.15 for hail and $6.03 for wind before any deductible; at the U.S. median county rates it would be $5.44 and $4.96.
  • If the next years look like 2014 to 2025, a roof kept 20 years in Story County meets about 45.0 hail days of 1 inch or more; the median county in NOAA's file (1,275 counties) would give 35.0.
  • Built in 1983, the median home in Story County is 43 years old, so an original roof has outlived a 3-tab shingle (15 to 20 years) and an architectural one (25 to 30 years); 69.3% of its 41,642 homes are at least 26 years old.
  • March to June holds 122 of the 153 hail reports in Story County (80 percent); the quietest month is January, with 0 reports.

What hail and wind cost a home here in an average year

Enter a home value. The calculator applies Story County’s own loss rate: the county’s expected yearly loss divided by the value of its buildings. It starts at the Census median home value for the county.

$5.15hail, a year; $5.44 at the U.S. median county rate
$6.03strong wind, a year; $4.96 at the U.S. median county rate
$224hail and wind together over 20 years, at today’s rate

Formula: home value × Story County yearly loss ÷ building value. Hail: $470,689 ÷ $22,246,186,929 = 0.0000212. Wind: $550,631 ÷ $22,246,186,929 = 0.0000248. This is FEMA’s estimate of average damage to buildings and does not account for your deductible. Tornado is left out because FEMA’s tornado loss counts people and other exposure, not only buildings.

Read this as a yardstick. The rate is an average over every building in the county, from sheds to office towers, and over many years. Real losses come in rare, large storms; a roof with no damage in 19 years can need full replacement in the 20th. The figure is not a quote and not a prediction for one address.

Story County in plain numbers

  • Story County scores 68.83 in FEMA's overall hazard index (Relatively Low): 981st of 3,144 rated counties and 9th of 99 in Iowa.
  • Hail scores 86.83 (Relatively Moderate). FEMA expects $470,689 of hail damage to buildings in Story County a year, which is $21 per $1 million of buildings, 0.95 times the U.S. median.
  • Strong wind scores 69.88 (Relatively Moderate) with $550,631 of expected yearly building loss in Story County: $25 per $1 million of buildings, 1.21 times the U.S. median.
  • Tornado scores 91.35 (Relatively High) and FEMA's expected yearly tornado loss is $10,363,004, counting everything exposed, or $466 per $1 million of buildings in Story County.
  • FEMA's own event record for Story County averages 6.20 hail events and 6.05 strong-wind events a year.
  • NOAA logged 153 hail reports in Story County between 2014 and June 2026, on 27 days with stones of 1 inch or more; the largest was 2.75 inches.
  • In Story County, FEMA counts buildings worth 22.25 billion dollars and 98,533 residents.
  • Social vulnerability is Very Low in Story County.
  • Community resilience there is Very High, for 98,533 residents.
  • 1 city in Story County is covered on this site: Ames. 15 Census ZIP areas have more than half of their land in the county.
  • Our guide range for a 2,000 sq ft asphalt roof in Ames is $6,090 to $13,485.
  • Story County ranks 104 of the 194 counties with a page here for hail loss per $1 million of buildings, 43 for wind and 30 for tornado.
  • In Story County, May is the busiest month with 52 of the 153 reports (34 percent), against 0 reports in November.
  • Story County's worst year was 2018, with 5 hail days at 1 inch or more and 30 reports. At the 2014 to 2025 pace that is 2.25 such days a year, one about every 5.3 months.
  • The median home in Story County was built in 1983; 47.5% of its 41,642 housing units date from before 1980, 69.3% from before 2000 and 15.5% from 2010 on.
  • Census puts the median home value in Story County at $243,600, and 56.0% of homes are lived in by their owners.
  • 2,309 single-family building permits were issued in Story County from 2014 to 2025, about 55.4 per 1,000 homes, peaking in 2018.
  • NOAA lists 12 tornado tracks in Story County since 2014; the strongest was an EF2 on May 21, 2024 near Cambridge, 23.29 miles long.
  • The fastest gust in NOAA's records for Story County is 100 mph on August 10, 2020 at Slater.
  • The nearest county with a page here is Black Hawk County, 66 miles from the centre of Story County; its hail score is 87.31.
  • Across counties the median is one roofing firm for every 5,189 homes; Census counted 3 roofing contractor establishments in Story County in 2023, one for every 13,881 homes.
  • FEMA has named Story County in 4 disaster declarations since 2014, the latest 14 days before its data end, and 4 of them were storm-type.

The hail record of Story County, year by year

NOAA logged 153 reports in Story County; hail of 1 inch or more fell on 27 days. That is 2.2 such days a year; the median county in NOAA’s file has 1.8.

Story County: NOAA hail reports per year, 2014 to June 2026, with the number of days that had hail of 1 inch or more05101520253035402014: 25 reports, 2 days at 1 inch or more, largest 2.75 inch142015: 2 reports, 0 days at 1 inch or more, largest 0.75 inch152016: 0 reports, 0 days at 1 inch or more, largest 0 inch162017: 9 reports, 4 days at 1 inch or more, largest 2 inch172018: 30 reports, 5 days at 1 inch or more, largest 2.25 inch182019: 8 reports, 1 days at 1 inch or more, largest 1.5 inch192020: 15 reports, 1 days at 1 inch or more, largest 2.5 inch202021: 1 reports, 0 days at 1 inch or more, largest 0.88 inch212022: 3 reports, 2 days at 1 inch or more, largest 1.25 inch222023: 36 reports, 3 days at 1 inch or more, largest 2.5 inch232024: 9 reports, 5 days at 1 inch or more, largest 1.25 inch242025: 15 reports, 4 days at 1 inch or more, largest 1.5 inch252026: 0 reports, 0 days at 1 inch or more, largest 0 inch26*
  • reports
  • days with hail of 1 inch or more
  • * 2026 runs to June only
Story County: NOAA hail reports by calendar month, 2014 to June 2026January: 0 reports0JanFebruary: 0 reports0FebMarch: 22 reports22MarApril: 33 reports33AprMay: 52 reports52MayJune: 15 reports15JunJuly: 17 reports17JulAugust: 5 reports5AugSeptember: 8 reports8SepOctober: 1 reports1OctNovember: 0 reports0NovDecember: 0 reports0Dec

Reports by calendar month, all years together. Peak: May, 52 reports.

The same numbers as a table (years with at least one report)
YearReportsDays, 1 inch or moreDays, 1.75 inch or moreLargest stoneDamage reported
201425222.75 in$467,000
20152000.75 in–
20179412 in$2,000
201830522.25 in$140,000
20198101.5 in–
202015112.5 in–
20211000.88 in–
20223201.25 in–
202336322.5 in$20,000
20249501.25 in–
202515401.5 in–

Biggest hail days in Story County

DateLargest stoneReports that dayDamage reportedNear
April 12, 20142.75 in17$205,000Roland
May 7, 20232.5 in15none recordedAmes
July 11, 20202.5 in14none recordedRoland
May 25, 20182.25 in10$85,000Huxley
May 1, 20182 in8$55,000Nevada

Where large hail was reported

FEMA scores the county as a whole. NOAA’s reports show where inside Story County the big stones fell.

Reported hail locations, Story County

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  • 891 to 1.74 in
  • 251.75 to 2.74 in, golf ball to tennis ball
  • 12.75 in and up, baseball

Largest plotted stone: 2.75 in. Bigger dots are bigger stones.

115 reports of 1 inch or larger have coordinates. Each dot is a reported location, not a storm path.

Sources: NOAA, Census county outline

Wind and tornado records for Story County

Fastest gusts in Story County

DateGustNear
August 10, 2020100 mphSlater
August 10, 2020100 mphZearing
June 7, 201586 mphAmes Arpt
June 7, 201586 mphAmes Arpt

Strongest tornado tracks in Story County

DateScaleLengthInjured / killedNear
May 21, 2024EF223.29 mi2 / 0Cambridge
June 7, 2015EF10.92 mi0 / 0Ames Arpt
July 19, 2018EF02.79 mi0 / 0Roland
July 19, 2018EF02.48 mi0 / 0Collins

12 tornado tracks in all since 2014; the strongest 4 are listed.

How old the roofs are

Census counts homes by the decade they were built. Under each bar is the number of hail days of 1 inch or more that an original roof from that decade has met, at Story County’s 2014 to 2025 pace of 2.25 such days a year. Most roofs have been replaced since; the row shows what a roof that never was would have taken.

Story County: share of homes by decade built, with the hail days at 1 inch or more that an original roof from each decade has met at the county's 2014 to 2025 ratepre-1940: 14.6% of homes14.6%<19402051940s: 2.6% of homes2.6%1940s1821950s: 7.1% of homes7.1%1950s1601960s: 9.6% of homes9.6%1960s1371970s: 13.7% of homes13.7%1970s1151980s: 7.6% of homes7.6%1980s921990s: 14.1% of homes14.1%1990s702000s: 15.2% of homes15.2%2000s472010s: 14.0% of homes14%2010s252020+: 1.4% of homes1.4%2020+7

Bars: share of 41,642 housing units by decade built. Figures under the decade: hail days met by an original roof, at the county’s 2014 to 2025 pace. The pace of earlier years is unknown.

Median year built1983
Built before 198047.5%
Built before 200069.3%
Built since 201015.5%
Owner-occupied56.0%
Median home value$243,600
Single-family permits, 2014 to 20252,309
Permits per 1,000 homes55.4

Asphalt shingles are rated 15 to 20 years (3-tab) and 25 to 30 years (architectural). Source: Census ACS 2019 to 2023 and Building Permits Survey.

Roofers and past disasters in Story County

Roofing firms in Story County

Roofing contractor establishments, 20233
Change since 2016+1 (+50%)
Homes per roofing firm13,881
Median across counties5,189
Employees, 202362

Source for Story County: Census County Business Patterns, NAICS 238160. Full roofing-market page for Story County.

FEMA disaster declarations naming Story County since 2014

Declarations naming Story County4
Storm / flood / winter / fire4 / 0 / 0 / 0
Median IA county3
Rank among 67 IA counties33
Days from the latest to the data cutoff14

Source for Story County: OpenFEMA, data to 2026-09-15. Declaration list for Story County.

Nearby counties

The closest counties that have a risk page, by distance between county centres. Loss is per $1 million of buildings; the columns marked "times here" divide the neighbour's loss by Story County's.

CountyMilesOverallHail lossHail, times hereWind lossWind, times hereNOAA hail reports
Black Hawk County, IA66 Relatively Low $261.25$261.0365
Linn County, IA96 Relatively Moderate $1095.14$251.02175
Johnson County, IA100 Relatively Moderate $1175.54$1726.97109
Pottawattamie County, IA119 Relatively Low $1275.98$552.2383
Woodbury County, IA136 Relatively Moderate $612.86$481.9592
Dubuque County, IA139 Relatively Low $1034.85$371.4863

More Iowa counties, nearest first

All 194 counties, with a filter by state and sorting

Cities and ZIP areas in Story County

1 city in this county is on PickARoofer. ZIP Code Tabulation Areas are Census shapes that approximate ZIP codes; where we have a city’s ZIPs, the share is the part of each area’s land that lies in this county. 15 such areas have more than half their land here.

CityZIP areas (share of land in the county)Pages
Ames 50010 (100%), 50014 (56%), 50012 (100%) Roofers

Storm hit your roof in Story County? A free inspection tells you if there is damage. One local roofer answers, not five.

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Questions

How high is storm risk in Story County?

FEMA's National Risk Index gives Story County an overall score of 68.83 (Relatively Low), 981st of 3,144. Hail scores 86.83 (Relatively Moderate), strong wind 69.88 (Relatively Moderate) and tornado 91.35 (Relatively High).

In Story County, how many hail reports has NOAA logged?

A report is one entry for one storm in one county, so counts follow where people live as well as where hail fell. NOAA has 153 for Story County between 2014 and June 2026, on 27 days with hail of 1 inch or more; the largest stone was 2.75 inches.

What do hail and wind cost a home in Story County each year, on average?

Applying FEMA's county rates to its median home value of $243,600: FEMA's estimate is about $5.15 a year for hail and $6.03 for wind, before any deductible, against $5.44 and $4.96 at the U.S. median county rates. This is an average over many years and all buildings, not a prediction for one roof; one bad storm costs far more than the average year.

How does Story County compare with the rest of Iowa?

Per $1 million of buildings Story County loses $21 to hail a year, against $51 in the median county of the state. Among 99 rated counties it is 22nd for hail, 32nd for strong wind and 8th for tornado.

How old are the roofs in Story County?

The median home was built in 1983, 43 years ago, and 69.3% of the 41,642 housing units in Story County date from before 2000. Asphalt shingles are rated 15 to 20 years (3-tab) or 25 to 30 years (architectural), so an original roof of either kind is past its rated life. The Census does not record when a roof was replaced.

What does expected annual loss mean?

It is FEMA's estimate of the average yearly loss from a hazard, in dollars, summed over the county. It is built for comparing counties at planning level, not for pricing one house.

Does a high rating mean my roof will be damaged?

No. The index compares counties and cannot say what will happen on your street. After a storm, a roof inspection is the only way to know.

Sources for Story County: FEMA National Risk Index, version December 2025, retrieved October 8, 2026; NOAA Storm Events Database hail reports for Story County; Census Bureau ZCTA-to-county relationship file (2020); Census ACS and Building Permits Survey, homes in Story County; Census County Business Patterns, roofing firms in Story County; OpenFEMA, declarations naming Story County. Planning-level information about Story County, not an inspection and not insurance advice.

This product uses the Federal Emergency Management Agency's National Risk Index dataset 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).