Hail history for Rock County, WI

Rock County has 173 recorded hail events in the NOAA Storm Events Database — 115 of them 1″ or larger and 15 at 2″ or larger. The largest on record: 3.0″ (tea cup) on June 4, 1975.

Records 1950–present Data through April 2026 Peak month April

Core sample · every recorded event, 1955–2026

Mark size = measured hail diameter; slivers are events with no recorded size. Amber ≥2″, red ≥2.75″ (baseball class). Denser recent decades partly reflect better reporting, not only more storms.

Recorded events 173 since 1961

1″ or larger 115 NWS severe threshold

2″ or larger 15 hen egg class and up

Largest recorded 3.0″ tea cup · June 4, 1975

Read the record honestly: Storm Events contains what was reported to the National Weather Service. Sparse or rural counties under-report, and coverage improved sharply after the mid-1990s — a quiet-looking stretch is not proof nothing fell.

When it hails in Rock County

Recorded events by month, 1950–present. The amber bar marks Rock County's peak: April.

Most recent recorded events

Latest 8 of 173 recorded events · data through April 2026
Date	Size	Comparable to
April 17, 2026	2.0″	Hen egg
April 17, 2026	1.75″	Golf ball
April 17, 2026	1.75″	Golf ball
April 17, 2026	1.5″	Ping-pong ball
April 2, 2026	1.25″	Half dollar
April 2, 2026	0.88″	Nickel
April 2, 2026	1.5″	Ping-pong ball
April 2, 2026	0.75″	Penny

Looking for a specific storm? Use the did-it-hail date lookup for Rock County.

From the storm reports

Narratives as filed with the NOAA Storm Events Database (public records; lightly trimmed for length).

August 16, 2025 · 1.5″ (ping-pong ball)

Ping pong ball hail on the west side of Janesville.

April 18, 2025 · 2.75″ (baseball)

Picture provided.

August 24, 2006 · 2.5″ (tennis ball)

Large hail ranging from 1.00 inch to 2.50 inches fell from 1 mile west of Footville to 4 miles west of Beloit.

Events by decade

1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s
0	3	5	4	17	54	36	54

The climb across decades is largely a reporting story: spotter networks, radar, and digital filing pulled far more storms into the record after the 1990s.

Questions about hail in Rock County

Has it ever hailed in Rock County?

Yes — 173 hail events have been recorded for Rock County, WI in the NOAA Storm Events Database since 1961, including 115 of 1″ (quarter size) or larger.

When did it last hail in Rock County?

The most recent recorded hail event for Rock County, WI is April 17, 2026, with 2.0″ (hen egg) hail. The database is currently updated through April 2026, so a storm from the last few weeks may not appear yet. To check a specific day, use the did-it-hail date lookup.

What is the largest hail ever recorded in Rock County?

3.0″ (tea cup), recorded on June 4, 1975. Hail that size is destructive-class and typically damages roofs, vehicles, and siding. See how big that really is on the actual-size hail chart.

Does a recorded hail event mean my roof was damaged?

No. This page reports storm records, not damage. Hail size and damage vary block by block within a county, and only an inspection can establish what happened to a specific roof. If you suspect damage, talk to your insurer or a licensed roofer — they can pull the same NOAA records for your claim.

More Wisconsin hail history

All 72 Wisconsin counties, ranked by recorded hail →

Source: NOAA/NCEI Storm Events Database, public domain, updated monthly by NCEI — this site's copy runs through April 2026. HailHistory reports records; it does not give insurance advice or assess damage.