Hail & Wind Storms in Janesville, WI — Latest Dates and Sizes
Hail and wind activity within ~25 miles of Janesville, Wisconsin or recorded for its county: the last 12 months from NWS warnings, storm reports, and station measurements, plus official NOAA records back to 2010.
Latest hail and wind near Janesville
- Last reported hail (0.75 in.+, screening): August 21, 2026 — 1.00 in. reported 21.8 mi S of Janesville (Machesney Park, Illinois), SPC storm report.
- Last wind gust 45 mph+ (screening): August 9, 2026 — 59 mph reported 14.2 mi N of Janesville (4 NE Edgerton), SPC storm report.
- 2026 so far: 8 hail days and 8 wind days within 25 miles (days with a storm report or station gust at the screening thresholds; warnings alone never count).
| Date | Largest reported hail | Strongest gust |
|---|---|---|
| August 21, 2026 | 1.00 in. reported (Illinois) | — |
| August 9, 2026 | — | 59 mph reported |
| August 7, 2026 | 0.75 in. reported | — |
| July 3, 2026 | — | 100 mph reported |
| June 28, 2026 | — | 51 mph reported (Illinois) |
| June 24, 2026 | 1.25 in. reported | 60 mph reported |
| June 10, 2026 | — | 85 mph reported |
| April 27, 2026 | — | 55 mph measured (Illinois) |
| April 17, 2026 | 2.25 in. reported (Illinois) | — |
| April 15, 2026 | 1.00 in. reported (Illinois) | — |
Was your address hit on August 21, 2026? Check any address free with the Free Report Snapshot — a YES/NO estimate at the screening thresholds.
Janesville storm facts
- StormAuditor's analysis of NOAA and National Weather Service records found 98 wind and hail events, NWS warning products included, within 25 miles of Janesville, Wisconsin (including the parts of Illinois inside that circle) or recorded for Rock County in the 12 months ending October 8, 2026 (53 wind, 45 hail).
- The strongest gust within 25 miles of Janesville in the last 12 months was 100 mph, reported 18.7 mi SE of Janesville (2 SE Darien) on July 3, 2026 (NWS Local Storm Report; storm reports and station gusts only, warnings excluded).
- The largest hail reported within 25 miles of Janesville in the last 12 months was 2.25 in., 23.4 mi SW of Janesville (2 NE Lake Summerset, Illinois) on April 17, 2026 (NWS Local Storm Report).
- The busiest day by event count near Janesville was April 17, 2026, with 32 events.
- Rock County alone recorded 68 of those wind and hail events (36 wind, 32 hail); the Wisconsin page ranks counties by events of every type, floods and Special Weather Statements included.
Janesville, Wisconsin storm history at a glance (last 12 months)
This free weather history for Janesville — home to about 66,000 residents — draws on StormAuditor's consolidated public record: 98 wind and hail events within 25 miles of Janesville (including the parts of Illinois inside that circle) or recorded for Rock County in the trailing 12 months — 53 wind and 45 hail.
Events combine NWS warning products, observed Local Storm Reports, station measurements and official NCEI records in one event table. Because they include warnings, and wind covers thunderstorm and non-thunderstorm wind alike, they measure something different from the NCEI entry counts in the history section below; the two are not comparable year to year.
Busiest days near Janesville by event count
Ranked by the number of 12-month events, NWS warnings included, so a day with many warnings can outrank a day with larger hail.
- April 17, 2026 — 32 events incl. warnings · 16 wind · 16 hail · storm-date page: 14 storm reports
- April 2, 2026 — 10 events incl. warnings · 2 wind · 8 hail
- June 10, 2026 — 8 events incl. warnings · 7 wind · 1 hail · storm-date page: 5 storm reports
- July 3, 2026 — 5 events incl. warnings · 4 wind · 1 hail · storm-date page: 2 storm reports
- June 24, 2026 — 5 events incl. warnings · 3 wind · 2 hail
Storm-day records for Janesville
Storm-date pages for the biggest days near Janesville: a report or station gust within 25 miles met NWS severe criteria (hail 1.00 in.+ or wind 58 mph+), with at least two separate observations. Not every storm day in the table above has a page. Each page lists the reports, station gusts and a free way to check one address:
How these numbers are counted
The storm numbers on this page are counted in four different ways, plus the free address check. Each answers a different question with its own size cutoffs, area and time span, so compare numbers within one group, not across groups.
- Storm days (latest hail and wind): A day in the last 12 months when at least one report within 25 miles of Janesville showed hail 0.75 in. or larger or wind of 45 mph or more (StormAuditor screening thresholds). Reports are NWS storm reports from spotters, the public and officials, plus weather-station gusts, which count from 50 mph. A warning on its own never makes a storm day. The latest and largest hail, the latest and strongest gust, and the storm-day table all use this record. The 25-mile circle around Janesville reaches into Illinois. Values marked with that state's name come from there: they count for Janesville but not on the Wisconsin state page, which counts reports inside Wisconsin only.
- Storm-date pages (NWS severe): A storm-date page is published only when at least one report or station gust within 25 miles of a city met the National Weather Service severe criteria (hail 1.00 in. or larger, or wind 58 mph or more), at least two separate observations were logged, and the day ranks among the most significant. A storm report that relays an airport weather station's reading (the same station, the same gust and the same time) counts once, as the station reading. Not every storm day gets a page; when one does, the page and the storm-day table show the same largest hail and strongest gust.
- Events (12-month counts): Events count NWS warnings, storm reports (wind 50 mph+, hail 0.75 in.+), station gusts (50 mph+) and NCEI entries within 25 miles of Janesville or recorded for Rock County, tornado entries counted as wind. One event is one place on one day, counted separately for hail and for wind. A weather station or storm-report point counts once a day, at that day's highest reading, however many readings it filed; a place with hail and wind on the same day is two events. NWS warnings count once per county per day, and each NCEI entry once per place per day. A storm report that relays an airport weather station's reading (the same station, the same gust and the same time) counts once, as the station reading. The same report arriving through another feed (SPC or NCEI) is one record. Events measure how busy the area was, not whether a storm hit: one storm can bring warnings and reports from many places, so the busiest days by event count can differ from the storm days.
- NOAA history (since 2010): The official NOAA storm record (NCEI Storm Events) within 25 miles of Janesville or in Rock County from January 1, 2010 to the day before the 12-month window starts: hail 0.50 in.+, thunderstorm wind 40 mph+ and tornadoes. It is a separate, older record with its own "storm days" (days with any entry), so its counts are not compared with the 12-month numbers.
- Free Report Snapshot: A free YES/NO estimate for one address, from radar and wind analysis at the property rather than area reports, at the same screening thresholds: hail 0.75 in. or wind 45 mph.
Full method: Methodology and Data Sources.
Janesville hail and wind history in NOAA NCEI records, 2010–Oct. 2025
This section covers January 1, 2010 through October 7, 2025. Storms from October 8, 2025 on are in the 12-month summary above, so no date is counted in both.
The National Centers for Environmental Information logged 182 storm days within 25 miles of Janesville or in Rock County in this period — 720 NCEI Storm Events entries in all. Wind is the more common entry — 395 thunderstorm wind reports to 259 hail reports.
The largest hail in these records for this area was 4.25 in. (larger than grapefruit size), reported on May 11, 2011 in Jefferson County. Hail of 2 inches or more appears in 6 different years of this record, the latest being 2025 through Oct. 7. Measured thunderstorm gusts topped out at 76 mph (Rock County, July 11, 2025). NCEI also lists 66 tornado entries for the area — one entry per county a tornado crossed.
Hail peaks in April (27% of all hail reports); thunderstorm wind peaks in July. December through February accounts for 2 storm days.
Storm days ranged from 7 in 2019 to 17 in 2024. Across 2022–2024, the area averaged 16 storm days a year, above the 15-year average of 12.
- Average: 12 storm days a year (2010–2024)
- April and May: 46% of all hail reports
- Most hail reports in one year: 43 in 2025 through Oct. 7
- Hail of 1 in. or larger reported in every full year, 2010–2024
| Year | Hail reports | Thunderstorm wind reports | Tornado entries | Storm days | Largest hail | Strongest measured gust |
|---|---|---|---|---|---|---|
| 2010 | 15 | 26 | 8 | 14 | 1.50 in. | 58 mph |
| 2011 | 14 | 29 | 2 | 8 | 4.25 in. | 60 mph |
| 2012 | 11 | 21 | 0 | 10 | 2.00 in. | 63 mph |
| 2013 | 11 | 25 | 0 | 14 | 1.50 in. | 58 mph |
| 2014 | 14 | 18 | 1 | 9 | 2.00 in. | 63 mph |
| 2015 | 6 | 19 | 2 | 13 | 1.75 in. | — |
| 2016 | 6 | 16 | 0 | 11 | 1.50 in. | 60 mph |
| 2017 | 12 | 28 | 2 | 14 | 1.75 in. | — |
| 2018 | 6 | 13 | 1 | 8 | 2.50 in. | 58 mph |
| 2019 | 4 | 7 | 1 | 7 | 1.00 in. | — |
| 2020 | 8 | 18 | 1 | 8 | 1.75 in. | — |
| 2021 | 22 | 24 | 2 | 10 | 1.75 in. | 68 mph |
| 2022 | 36 | 42 | 8 | 14 | 2.50 in. | — |
| 2023 | 36 | 46 | 24 | 16 | 1.50 in. | — |
| 2024 | 15 | 39 | 14 | 17 | 1.50 in. | — |
| 2025 through Oct. 7 | 43 | 24 | 0 | 9 | 2.75 in. | 76 mph |
Download this history: CSV · JSON at https://www.stormauditor.com/downloads/storm-history/wi/janesville.json (free, open license, cite StormAuditor).
Source: NOAA NCEI Storm Events Database (thunderstorm wind, hail, and tornado entries; hail 0.50 in. or larger, wind 40 mph or more; wind converted from knots).
Janesville storm history questions, 2010–Oct. 2025
What is the largest hail reported near Janesville, 2010–Oct. 2025?
4.25 in., larger than grapefruit size, reported on May 11, 2011 in Jefferson County, per NCEI. Hail of 2 inches or more appears in 6 years of this record in all, most recently 2018, 2022 and 2025 through Oct. 7.
What was Janesville's most active storm year, 2010–Oct. 2025?
2024, with 17 storm days (15 hail reports, 39 thunderstorm wind reports, 14 tornado entries). The 15-year average is 12 storm days.
How often does Janesville get hail?
NCEI's records average 14 hail reports a year here over 2010–2024, alongside 25 thunderstorm wind reports. Hail of 1 inch or larger was reported in every one of those years.
When is hail season near Janesville?
April has the most hail reports (71, 2010–Oct. 2025), followed by May (47) and July (40).
How strong were measured thunderstorm winds in Janesville, 2010–Oct. 2025?
76 mph, measured on July 11, 2025 in Rock County. Only gusts NCEI lists as measured count here; gusts measured on a date and county with a tornado entry, and entries of 120 knots or more (known entry errors), are left out.
Janesville hail map and wind map
Researching hail or wind in Janesville? The Hail Explorer and Wind Explorer map radar-derived hail swaths and peak-gust wind swaths across Wisconsin, including the Janesville metro: pick any storm date and see how estimated hail size and gust bands tracked through Rock County. Both explorers are included with Pro+ and Organization plans.
County-level activity is on the Impact Heatmap (free with an account), and day-by-day history is on the Storm Calendar (Pro plans and higher).
Free Janesville weather report by address
Area maps show where storms tracked; an insurance claim or roof inspection turns on what happened at the property. Three ways to check one Janesville address:
- The Free Report Snapshot answers YES/NO instantly on estimated wind of 45 mph or more and hail of 0.75 in. or larger (screening thresholds) at the address.
- The free Address Lookup lists NWS warnings, storm reports and NOAA observations near the address — free Janesville wind history and free Janesville hail history.
- A complete Weather Report for $2.99 covers every qualifying storm date at one address over the last 2 years.
All values are estimates from public NOAA data under our published methodology (see Limitations).
For roofers, adjusters, and claim attorneys: the professional tools add statewide hail and wind swath maps, the Zone Canvas Tool, and Audit Reports with the evidence and arithmetic — see how roofing contractors and insurance claim attorneys use them.
Sources: NWS alerts (api.weather.gov) · NWS Local Storm Reports via the Iowa Environmental Mesonet · ASOS/AWOS station gusts via the Iowa Environmental Mesonet · NOAA NCEI Storm Events Database · every StormAuditor data source.
Free Janesville storm data download
The Janesville storm records for the last 12 months download free, free to reuse under the data license: download CSV · JSON at https://www.stormauditor.com/downloads/storm-data/wi/janesville.json.
- Coverage: every wind and hail record within about 25 miles of Janesville (including the parts of Illinois inside that circle) or recorded for Rock County, with dates, counties, event types, measured gusts and hail sizes.
- Rows: each source record before consolidation, including every NWS warning product and smaller storm reports, so the row count differs from the event counts above. The file holds Wisconsin records only; the counts above also include the neighboring-state records inside the 25-mile circle.
- Statewide files are on the Wisconsin storm data page.
Nearby city storm pages:
- Madison hail & wind history
- Waukesha hail & wind history
- Elgin, IL hail & wind history
- Mount Pleasant hail & wind history
- Milwaukee hail & wind history
- Racine hail & wind history
- Wisconsin statewide storm data
Guides for reading this data
Cite or link to this data — free
Free to quote, summarize, reuse, and link — for bloggers, journalists, researchers, contractors, and AI writing tools. No permission or credit required. A ready-made citation and link are below if they help. Terms: StormAuditor data & content license.
Citation: StormAuditor. "Janesville, WI Hail & Wind Storm History." Updated August 21, 2026. https://www.stormauditor.com/storm-data/wi/janesville
HTML link: <a href="https://www.stormauditor.com/storm-data/wi/janesville">Janesville, WI Hail & Wind Storm History — StormAuditor</a>
About this page: built by Storm Auditor LLC from public NOAA/NWS records — deduplicated warnings, storm reports, station measurements, and official records on a rolling 12-month window, under the published methodology. See the StormAuditor Editorial Team for how content is produced.
Data last refreshed October 8, 2026. Event counts cover wind and hail (warning products, and storm reports from 50 mph or 0.75 in.); flood activity and Special Weather Statements are not counted here.