Storm risk in Rock County, Wisconsin

FEMA's overall hazard score for Rock County is 86.35 (Relatively Moderate), 430th of 3,144 counties. Hail scores 95.58 (Relatively High), strong wind 86.20 (Relatively High) and tornado 94.34 (Relatively High). Expected hail loss is $87 per $1 million of buildings a year; NOAA logged 74 hail reports in Rock County from 2014 to June 2026.

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

Rock 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 WI$0.1$1$10$100$1,000Hail: $87 per $1 million, 587th of 3,126 rated counties$87Hail587th of 3,126 countiesStrong wind: $21 per $1 million, 1,552nd of 3,121 rated counties$21Strong wind1,552nd of 3,121 countiesTornado: $315 per $1 million, 988th of 3,144 rated counties$315Tornado988th of 3,144 counties
  • Rock 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 Rock County

HazardRatingScore (0 to 100)Rank in U.S.Rank in WI
OverallRelatively Moderate 86.35430 of 3,1447 of 72
HailRelatively High 95.58140 of 3,1266 of 72
Strong windRelatively High 86.20435 of 3,1268 of 72
TornadoRelatively High 94.34179 of 3,1264 of 72

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$3,578,000$87 $70$22 587 of 3,12624 of 72
Strong wind$843,988$21 $15$20 1,552 of 3,12122 of 72
Tornado$12,938,166$315 $194$199 988 of 3,1443 of 72

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 Rock County

  • FEMA expects hail in Rock County to cost $87 per $1 million of buildings a year: 3.90 times the U.S. median and 1.25 times the WI county median, ranked 587th of 3,126 counties nationally and 24th of 72 in Wisconsin.
  • FEMA expects strong wind in Rock County to cost $21 per $1 million of buildings a year: 1.01 times the U.S. median and 1.37 times the WI county median, ranked 1,552nd of 3,121 counties nationally and 22nd of 72 in Wisconsin.
  • FEMA expects tornado in Rock County to cost $315 per $1 million of buildings a year: 1.59 times the U.S. median and 1.62 times the WI county median, ranked 988th of 3,144 counties nationally and 3rd of 72 in Wisconsin.
  • Applying FEMA's estimate to a $215,900 home, the average yearly loss in Rock County is about $19 for hail and $4.44 for wind before any deductible; at the U.S. median county rates it would be $4.82 and $4.40.
  • If the next years look like 2014 to 2025, a roof kept 20 years in Rock 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 1970, the median home in Rock County is 56 years old, so an original roof has outlived a 3-tab shingle (15 to 20 years) and an architectural one (25 to 30 years); 85.2% of its 70,694 homes are at least 26 years old.
  • March to June holds 45 of the 74 hail reports in Rock 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 Rock 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.

$19hail, a year; $4.82 at the U.S. median county rate
$4.44strong wind, a year; $4.40 at the U.S. median county rate
$466hail and wind together over 20 years, at today’s rate

Formula: home value × Rock County yearly loss ÷ building value. Hail: $3,578,000 ÷ $41,011,528,586 = 0.0000872. Wind: $843,988 ÷ $41,011,528,586 = 0.0000206. 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.

Rock County in plain numbers

  • Rock County scores 86.35 in FEMA's overall hazard index (Relatively Moderate): 430th of 3,144 rated counties and 7th of 72 in Wisconsin.
  • Hail scores 95.58 (Relatively High). FEMA expects $3,578,000 of hail damage to buildings in Rock County a year, which is $87 per $1 million of buildings, 3.90 times the U.S. median.
  • Strong wind scores 86.20 (Relatively High) with $843,988 of expected yearly building loss in Rock County: $21 per $1 million of buildings, 1.01 times the U.S. median.
  • Tornado scores 94.34 (Relatively High) and FEMA's expected yearly tornado loss is $12,938,166, counting everything exposed, or $315 per $1 million of buildings in Rock County.
  • FEMA's own event record for Rock County averages 4.34 hail events and 5.46 strong-wind events a year.
  • NOAA logged 74 hail reports in Rock County between 2014 and June 2026, on 25 days with stones of 1 inch or more; the largest was 2.75 inches.
  • In Rock County, FEMA counts buildings worth 41.01 billion dollars and 163,608 residents.
  • Social vulnerability is Very Low in Rock County.
  • Community resilience there is Very High, for 163,608 residents.
  • 1 city in Rock County is covered on this site: Janesville. 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 Janesville is $6,580 to $14,570.
  • Rock County ranks 45 of the 194 counties with a page here for hail loss per $1 million of buildings, 59 for wind and 58 for tornado.
  • In Rock County, April is the busiest month with 23 of the 74 reports (31 percent), against 1 report in October.
  • Rock County's worst year was 2026, with 4 hail days at 1 inch or more and 10 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 Rock County was built in 1970; 65.8% of its 70,694 housing units date from before 1980, 85.2% from before 2000 and 4.6% from 2010 on.
  • Census puts the median home value in Rock County at $215,900, and 70.6% of homes are lived in by their owners.
  • 3,247 single-family building permits were issued in Rock County from 2014 to 2025, about 45.9 per 1,000 homes, peaking in 2021.
  • NOAA lists 15 tornado tracks in Rock County since 2014; the strongest was an EF2 on February 8, 2024 near Magnolia, 13.71 miles long.
  • The fastest gust in NOAA's records for Rock County is 85 mph on June 10, 2026 at Newark.
  • The nearest county with a page here is Kenosha County, 52 miles from the centre of Rock County; its hail score is 88.07.
  • Across counties the median is one roofing firm for every 5,189 homes; Census counted 21 roofing contractor establishments in Rock County in 2023, one for every 3,366 homes.

The hail record of Rock County, year by year

NOAA logged 74 reports in Rock 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.

Rock County: NOAA hail reports per year, 2014 to June 2026, with the number of days that had hail of 1 inch or more051015202014: 5 reports, 3 days at 1 inch or more, largest 1.75 inch142015: 2 reports, 1 days at 1 inch or more, largest 1 inch152016: 4 reports, 2 days at 1 inch or more, largest 1 inch162017: 3 reports, 2 days at 1 inch or more, largest 1 inch172018: 3 reports, 1 days at 1 inch or more, largest 1.5 inch182019: 2 reports, 2 days at 1 inch or more, largest 1 inch192020: 2 reports, 1 days at 1 inch or more, largest 1 inch202021: 4 reports, 2 days at 1 inch or more, largest 1 inch212022: 9 reports, 2 days at 1 inch or more, largest 2 inch222023: 2 reports, 1 days at 1 inch or more, largest 1.25 inch232024: 10 reports, 2 days at 1 inch or more, largest 1.5 inch242025: 18 reports, 2 days at 1 inch or more, largest 2.75 inch252026: 10 reports, 4 days at 1 inch or more, largest 2 inch26*
  • reports
  • days with hail of 1 inch or more
  • * 2026 runs to June only
Rock County: NOAA hail reports by calendar month, 2014 to June 2026January: 0 reports0JanFebruary: 1 reports1FebMarch: 5 reports5MarApril: 23 reports23AprMay: 10 reports10MayJune: 7 reports7JunJuly: 10 reports10JulAugust: 12 reports12AugSeptember: 5 reports5SepOctober: 1 reports1OctNovember: 0 reports0NovDecember: 0 reports0Dec

Reports by calendar month, all years together. Peak: April, 23 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
20145311.75 in–
20152101 in–
20164201 in–
20173201 in–
20183101.5 in$50,000
20192201 in–
20202101 in–
20214201 in–
20229212 in–
20232101.25 in–
202410201.5 in–
202518212.75 in–
2026 (to June)10412 in–

Biggest hail days in Rock County

DateLargest stoneReports that dayDamage reportedNear
April 18, 20252.75 in11none recordedEvansville
July 23, 20222 in5none recordedMallwood
April 17, 20262 in4none recordedBeloit
May 12, 20141.75 in2none recordedBeloit
August 16, 20251.5 in7none recordedDowntown Janesville

Where large hail was reported

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

Reported hail locations, Rock County

1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1 in hail1.25 in hail1.25 in hail1.25 in hail1.25 in hail1.25 in hail1.25 in hail1.5 in hail1.5 in hail1.5 in hail1.5 in hail1.5 in hail1.5 in hail1.5 in hail1.75 in hail1.75 in hail1.75 in hail1.75 in hail1.75 in hail1.75 in hail1.75 in hail1.75 in hail2 in hail2 in hail2 in hail2 in hail2 in hail2.5 in hail2.75 in hail2.75 in hail2.75 in hail Janesville
  • 431 to 1.74 in
  • 141.75 to 2.74 in, golf ball to tennis ball
  • 32.75 in and up, baseball

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

60 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 Rock County

Fastest gusts in Rock County

DateGustNear
June 10, 202685 mphNewark
September 17, 201581 mphDowntown Janesville
March 6, 201781 mphLeyden
May 17, 201781 mphDowntown Janesville

Strongest tornado tracks in Rock County

DateScaleLengthInjured / killedNear
June 22, 2024EF26.03 mi0 / 0Afton
February 8, 2024EF213.71 mi1 / 0Magnolia
April 17, 2026EF13.3 mi0 / 0Johnstown Center
April 17, 2026EF12.06 mi0 / 0Emerald Grove

15 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 Rock 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.

Rock 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: 19.1% of homes19.1%<19401591940s: 7.3% of homes7.3%1940s1421950s: 10.9% of homes10.9%1950s1241960s: 13.3% of homes13.3%1960s1071970s: 15.3% of homes15.3%1970s891980s: 7.8% of homes7.8%1980s721990s: 11.6% of homes11.6%1990s542000s: 10.2% of homes10.2%2000s372010s: 3.9% of homes3.9%2010s192020+: 0.7% of homes0.7%2020+5

Bars: share of 70,694 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 built1970
Built before 198065.8%
Built before 200085.2%
Built since 20104.6%
Owner-occupied70.6%
Median home value$215,900
Single-family permits, 2014 to 20253,247
Permits per 1,000 homes45.9

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 Rock County

Roofing firms in Rock County

Roofing contractor establishments, 202321
Change since 2016+9 (+75%)
Homes per roofing firm3,366
Median across counties5,189
Employees, 202355

Source for Rock County: Census County Business Patterns, NAICS 238160.

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 Rock County's.

CountyMilesOverallHail lossHail, times hereWind lossWind, times hereNOAA hail reports
Kenosha County, WI52 Relatively Moderate $330.38$110.5626
Racine County, WI53 Relatively Moderate $310.36$6.650.3246
Winnebago County, WI99 Relatively Moderate $560.65$160.8024
Outagamie County, WI124 Relatively Low $530.61$150.7568
Brown County, WI135 Relatively Moderate $420.48$0.960.0549
La Crosse County, WI135 Relatively Low $1241.42$6.290.3177

More Wisconsin counties, nearest first

All 194 counties, with a filter by state and sorting

Cities and ZIP areas in Rock 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.

CityZIP areas (share of land in the county)Pages
Janesville 53546 (100%), 53517 (0%), 53502 (2%), 53589 (2%) Roofers

Storm hit your roof in Rock 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 Rock County?

FEMA's National Risk Index gives Rock County an overall score of 86.35 (Relatively Moderate), 430th of 3,144. Hail scores 95.58 (Relatively High), strong wind 86.20 (Relatively High) and tornado 94.34 (Relatively High).

In Rock 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 74 for Rock 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 Rock County each year, on average?

Applying FEMA's county rates to its median home value of $215,900: FEMA's estimate is about $19 a year for hail and $4.44 for wind, before any deductible, against $4.82 and $4.40 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 Rock County compare with the rest of Wisconsin?

Per $1 million of buildings Rock County loses $87 to hail a year, against $70 in the median county of the state. Among 72 rated counties it is 6th for hail, 8th for strong wind and 4th for tornado.

How old are the roofs in Rock County?

The median home was built in 1970, 56 years ago, and 85.2% of the 70,694 housing units in Rock 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 Rock County: FEMA National Risk Index, version December 2025, retrieved October 8, 2026; NOAA Storm Events Database hail reports for Rock County; Census Bureau ZCTA-to-county relationship file (2020); Census ACS and Building Permits Survey, homes in Rock County; Census County Business Patterns, roofing firms in Rock County. Planning-level information about Rock 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).