Storm risk in Johnson County, Iowa
FEMA's overall hazard score for Johnson County is 87.44 (Relatively Moderate), 396th of 3,144 counties. Hail scores 95.26 (Relatively High), strong wind 98.92 (Very High) and tornado 98.19 (Relatively High). Expected hail loss is $117 per $1 million of buildings a year; NOAA logged 109 hail reports in Johnson County from 2014 to June 2026.
FEMA National Risk Index, version December 2025, retrieved October 8, 2026. NOAA hail reports 2014 to June 2026.
- Johnson 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 Johnson County
| Hazard | Rating | Score (0 to 100) | Rank in U.S. | Rank in IA |
|---|---|---|---|---|
| Overall | Relatively Moderate | 87.44 | 396 of 3,144 | 2 of 99 |
| Hail | Relatively High | 95.26 | 150 of 3,126 | 8 of 99 |
| Strong wind | Very High | 98.92 | 35 of 3,126 | 2 of 99 |
| Tornado | Relatively High | 98.19 | 58 of 3,126 | 1 of 99 |
Expected yearly loss, in dollars
| Hazard | This county, total a year | Per $1M of buildings | State median county | U.S. median county | Rank per $1M, U.S. | Rank per $1M, state |
|---|---|---|---|---|---|---|
| Hail | $3,997,526 | $117 | $51 | $22 | 419 of 3,126 | 12 of 99 |
| Strong wind | $5,884,543 | $172 | $66 | $20 | 89 of 3,121 | 4 of 99 |
| Tornado | $36,235,301 | $1,062 | $417 | $199 | 13 of 3,144 | 2 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 Johnson County
- FEMA expects hail in Johnson County to cost $117 per $1 million of buildings a year: 5.24 times the U.S. median and 2.27 times the IA county median, ranked 419th of 3,126 counties nationally and 12th of 99 in Iowa.
- FEMA expects strong wind in Johnson County to cost $172 per $1 million of buildings a year: 8.46 times the U.S. median and 2.60 times the IA county median, ranked 89th of 3,121 counties nationally and 4th of 99 in Iowa.
- FEMA expects tornado in Johnson County to cost $1,062 per $1 million of buildings a year: 5.33 times the U.S. median and 2.54 times the IA county median, ranked 13th of 3,144 counties nationally and 2nd of 99 in Iowa.
- Applying FEMA's estimate to a $293,100 home, the average yearly loss in Johnson County is about $34 for hail and $51 for wind before any deductible; at the U.S. median county rates it would be $6.55 and $5.97.
- If the next years look like 2014 to 2025, a roof kept 20 years in Johnson County meets about 35.0 hail days of 1 inch or more; the median county in NOAA's file (1,275 counties) would give 35.0.
- Built in 1991, the median home in Johnson County is 35 years old, so an original roof has outlived a 3-tab shingle (15 to 20 years) and an architectural one (25 to 30 years); 63.9% of its 67,211 homes are at least 26 years old.
- March to June holds 66 of the 109 hail reports in Johnson County (61 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 Johnson 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.
Formula: home value × Johnson County yearly loss ÷ building value. Hail: $3,997,526 ÷ $34,132,529,446 = 0.0001171. Wind: $5,884,543 ÷ $34,132,529,446 = 0.0001724. 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.
Johnson County in plain numbers
- Johnson County scores 87.44 in FEMA's overall hazard index (Relatively Moderate): 396th of 3,144 rated counties and 2nd of 99 in Iowa.
- Hail scores 95.26 (Relatively High). FEMA expects $3,997,526 of hail damage to buildings in Johnson County a year, which is $117 per $1 million of buildings, 5.24 times the U.S. median.
- Strong wind scores 98.92 (Very High) with $5,884,543 of expected yearly building loss in Johnson County: $172 per $1 million of buildings, 8.46 times the U.S. median.
- Tornado scores 98.19 (Relatively High) and FEMA's expected yearly tornado loss is $36,235,301, counting everything exposed, or $1,062 per $1 million of buildings in Johnson County.
- FEMA's own event record for Johnson County averages 4.44 hail events and 6.41 strong-wind events a year.
- NOAA logged 109 hail reports in Johnson County between 2014 and June 2026, on 25 days with stones of 1 inch or more; the largest was 2.75 inches.
- In Johnson County, FEMA counts buildings worth 34.13 billion dollars and 152,809 residents.
- Social vulnerability is Very Low in Johnson County.
- Community resilience there is Very High, for 152,809 residents.
- 1 city in Johnson County is covered on this site: Iowa City. 13 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 Iowa City is $6,090 to $13,485.
- Johnson County ranks 30 of the 194 counties with a page here for hail loss per $1 million of buildings, 4 for wind and 2 for tornado.
- In Johnson County, May is the busiest month with 20 of the 109 reports (18 percent), against 2 reports in November.
- Johnson County's worst year was 2017, with 5 hail days at 1 inch or more and 20 reports. At the 2014 to 2025 pace that is 1.75 such days a year, one about every 6.9 months.
- The median home in Johnson County was built in 1991; 37.8% of its 67,211 housing units date from before 1980, 63.9% from before 2000 and 19.8% from 2010 on.
- Census puts the median home value in Johnson County at $293,100, and 58.8% of homes are lived in by their owners.
- 6,069 single-family building permits were issued in Johnson County from 2014 to 2025, about 90.3 per 1,000 homes, peaking in 2014.
- NOAA lists 16 tornado tracks in Johnson County since 2014; the strongest was an EF2 on March 31, 2023 near Cosgrove, 16.93 miles long.
- The fastest gust in NOAA's records for Johnson County is 83 mph on August 28, 2018 at Iowa City Muni Arpt.
- The nearest county with a page here is Linn County, 30 miles from the centre of Johnson County; its hail score is 97.61.
- Across counties the median is one roofing firm for every 5,189 homes; Census counted 15 roofing contractor establishments in Johnson County in 2023, one for every 4,481 homes.
- FEMA has named Johnson County in 2 disaster declarations since 2014, the latest 2220 days before its data end, and 2 of them were storm-type.
The hail record of Johnson County, year by year
NOAA logged 109 reports in Johnson County; hail of 1 inch or more fell on 25 days. That is 1.8 such days a year; the median county in NOAA’s file has 1.8.
- reports
- days with hail of 1 inch or more
- * 2026 runs to June only
Reports by calendar month, all years together. Peak: May, 20 reports.
The same numbers as a table (years with at least one report)
| Year | Reports | Days, 1 inch or more | Days, 1.75 inch or more | Largest stone | Damage reported |
|---|---|---|---|---|---|
| 2014 | 14 | 2 | 1 | 1.75 in | – |
| 2015 | 3 | 0 | 0 | 0.75 in | – |
| 2016 | 1 | 0 | 0 | 0.75 in | – |
| 2017 | 20 | 5 | 0 | 1.5 in | – |
| 2018 | 7 | 1 | 0 | 1 in | – |
| 2020 | 11 | 2 | 1 | 1.75 in | – |
| 2023 | 15 | 5 | 1 | 1.75 in | – |
| 2024 | 14 | 5 | 1 | 1.75 in | – |
| 2025 | 3 | 1 | 0 | 1 in | – |
| 2026 (to June) | 21 | 4 | 2 | 2.75 in | – |
Biggest hail days in Johnson County
| Date | Largest stone | Reports that day | Damage reported | Near |
|---|---|---|---|---|
| March 10, 2026 | 2.75 in | 12 | none recorded | Oasis |
| July 11, 2020 | 1.75 in | 10 | none recorded | North Liberty |
| June 16, 2014 | 1.75 in | 5 | none recorded | Iowa City |
| June 25, 2024 | 1.75 in | 3 | none recorded | Solon |
| March 31, 2023 | 1.75 in | 2 | none recorded | North Liberty |
Where large hail was reported
FEMA scores the county as a whole. NOAA’s reports show where inside Johnson County the big stones fell.
Reported hail locations, Johnson County
- 611 to 1.74 in
- 81.75 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.
70 reports of 1 inch or larger have coordinates. Each dot is a reported location, not a storm path.
Sources: NOAA, Census county outlineWind and tornado records for Johnson County
Fastest gusts in Johnson County
| Date | Gust | Near |
|---|---|---|
| August 28, 2018 | 83 mph | Iowa City Muni Arpt |
| August 28, 2018 | 82 mph | University Hgts |
| April 12, 2014 | 81 mph | Iowa City |
| April 27, 2014 | 81 mph | Iowa City |
Strongest tornado tracks in Johnson County
| Date | Scale | Length | Injured / killed | Near |
|---|---|---|---|---|
| March 31, 2023 | EF2 | 16.93 mi | 2 / 0 | Cosgrove |
| March 31, 2023 | EF2 | 14.69 mi | 0 / 0 | Hills |
| March 31, 2023 | EF2 | 4.19 mi | 0 / 0 | Solon |
| May 24, 2024 | EF1 | 11.49 mi | 0 / 0 | River Jct |
16 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 Johnson County’s 2014 to 2025 pace of 1.75 such days a year. Most roofs have been replaced since; the row shows what a roof that never was would have taken.
Bars: share of 67,211 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 built | 1991 |
| Built before 1980 | 37.8% |
| Built before 2000 | 63.9% |
| Built since 2010 | 19.8% |
| Owner-occupied | 58.8% |
| Median home value | $293,100 |
| Single-family permits, 2014 to 2025 | 6,069 |
| Permits per 1,000 homes | 90.3 |
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 Johnson County
Roofing firms in Johnson County
| Roofing contractor establishments, 2023 | 15 |
| Change since 2016 | +0 (+0%) |
| Homes per roofing firm | 4,481 |
| Median across counties | 5,189 |
| Employees, 2023 | 75 |
Source for Johnson County: Census County Business Patterns, NAICS 238160.
FEMA disaster declarations naming Johnson County since 2014
| Declarations naming Johnson County | 2 |
| Storm / flood / winter / fire | 2 / 0 / 0 / 0 |
| Median IA county | 3 |
| Rank among 67 IA counties | 56 |
| Days from the latest to the data cutoff | 2,220 |
Source for Johnson County: OpenFEMA, data to 2026-09-15.
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 Johnson County's.
| County | Miles | Overall | Hail loss | Hail, times here | Wind loss | Wind, times here | NOAA hail reports |
|---|---|---|---|---|---|---|---|
| Linn County, IA | 30 | Relatively Moderate | $109 | 0.93 | $25 | 0.15 | 175 |
| Scott County, IA | 51 | Relatively Moderate | $93 | 0.80 | $22 | 0.13 | 128 |
| Black Hawk County, IA | 68 | Relatively Low | $26 | 0.23 | $26 | 0.15 | 65 |
| Dubuque County, IA | 71 | Relatively Low | $103 | 0.88 | $37 | 0.21 | 63 |
| Story County, IA | 100 | Relatively Low | $21 | 0.18 | $25 | 0.14 | 153 |
| Pottawattamie County, IA | 207 | Relatively Low | $127 | 1.08 | $55 | 0.32 | 83 |
More Iowa counties, nearest first
- Woodbury County 236 mi
Cities and ZIP areas in Johnson 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. 13 such areas have more than half their land here.
| City | ZIP areas (share of land in the county) | Pages |
|---|---|---|
| Iowa City | 52240 (100%), 52246 (100%), 52245 (100%), 52241 (100%) | Roofers |
Storm hit your roof in Johnson County? A free inspection tells you if there is damage. One local roofer answers, not five.
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How high is storm risk in Johnson County?
FEMA's National Risk Index gives Johnson County an overall score of 87.44 (Relatively Moderate), 396th of 3,144. Hail scores 95.26 (Relatively High), strong wind 98.92 (Very High) and tornado 98.19 (Relatively High).
In Johnson 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 109 for Johnson County between 2014 and June 2026, on 25 days with hail of 1 inch or more; the largest stone was 2.75 inches.
What do hail and wind cost a home in Johnson County each year, on average?
Applying FEMA's county rates to its median home value of $293,100: FEMA's estimate is about $34 a year for hail and $51 for wind, before any deductible, against $6.55 and $5.97 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 Johnson County compare with the rest of Iowa?
Per $1 million of buildings Johnson County loses $117 to hail a year, against $51 in the median county of the state. Among 99 rated counties it is 8th for hail, 2nd for strong wind and 1st for tornado.
How old are the roofs in Johnson County?
The median home was built in 1991, 35 years ago, and 63.9% of the 67,211 housing units in Johnson 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 Johnson County: FEMA National Risk Index, version December 2025, retrieved October 8, 2026; NOAA Storm Events Database hail reports for Johnson County; Census Bureau ZCTA-to-county relationship file (2020); Census ACS and Building Permits Survey, homes in Johnson County; Census County Business Patterns, roofing firms in Johnson County; OpenFEMA, declarations naming Johnson County. Planning-level information about Johnson 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).