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Tornado in Stephenson County, Illinois
23 tornadoes events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Tornado.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 23 tornado events in Stephenson County, Illinois, between 1950 and 2026, spread over 14 years.
June is the busiest month, with 7 of the recorded events. The last 20 years account for 12 events against 8 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.6% of the 3,647 tornado events recorded in Illinois; its 4.1 per 100 square miles compares with 6.6 statewide.
By rating: 11 at (E)F0, 6 at (E)F1, 2 at (E)F2, 0 at (E)F3, 0 at (E)F4, 0 at (E)F5 and 4 unrated. Tornadoes before 2007 carry the original Fujita rating.
Compared with Illinois
| Measure | Stephenson County | Illinois | US |
|---|---|---|---|
| Tornado events since 1950 | 23 | 3,647 | 81,281 |
| Per 100 square miles | 4.1 | 6.6 | 2.3 |
| Per 10,000 residents | 5.2 | 2.9 | 2.4 |
| Deaths recorded | 0 | 236 | 6,410 |
| Busiest month | June | April | May |
By year
Seasonality
0Feb
0Mar
2Apr
3May
3Jun
7Jul
3Aug
4Sep
0Oct
1Nov
0Dec
0
Magnitude distribution
Enhanced Fujita scale wind estimates
- EF0/F0
- 65–85 mph (EF0)
- EF1/F1
- 86–110 mph (EF1)
- EF2/F2
- 111–135 mph (EF2)
- EF3/F3
- 136–165 mph (EF3)
- EF4/F4
- 166–200 mph (EF4)
- EF5/F5
- over 200 mph (EF5)
- Unrated
- no rating recorded
Tornado rating as recorded (Fujita scale before February 2007, Enhanced Fujita after).
Recorded events
All 23 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 17 Apr 2026 | Tornado | EF2 | — | — | — | — | County |
| 14 Apr 2026 | Tornado | EF1 | — | — | — | — | County |
| 15 Jul 2024 | Tornado | EF unrated | — | — | — | — | County |
| 15 Jul 2024 | Tornado | EF unrated | — | — | — | — | County |
| 4 Mar 2024 | Tornado | EF unrated | — | — | — | — | County |
| 31 Mar 2023 | Tornado | EF unrated | — | — | — | — | County |
| 25 May 2022 | Tornado | EF1 | — | — | — | — | County |
| 10 Aug 2020 | Tornado | EF0 | — | — | — | — | County |
| 16 Aug 2017 | Tornado | EF1 | — | — | — | — | County |
| 16 Aug 2017 | Tornado | EF0 | — | — | — | — | County |
| 12 Jul 2010 | Tornado | EF0 | — | — | — | — | County |
| 1 Jun 2009 | Tornado | EF0 | $100K | — | — | — | County |
| 14 Jun 2003 | Tornado | F0 | — | $1K | — | — | County |
| 14 Jun 2003 | Tornado | F0 | — | $1K | — | — | County |
| 14 Jun 2003 | Tornado | F0 | — | $15K | — | — | County |
| 6 Jun 1999 | Tornado | F0 | — | — | — | — | County |
| 1 Jun 1999 | Tornado | F0 | — | — | — | — | County |
| 24 Aug 1998 | Tornado | F1 | $80K | — | — | — | County |
| 28 May 1998 | Tornado | F0 | — | — | — | — | County |
| 28 May 1998 | Tornado | F0 | $1K | — | — | — | County |
| 1 Jun 1971 | Tornado | F1 | $250K | — | — | — | County |
| 17 Apr 1959 | Tornado | F1 | $25K | — | — | — | County |
| 8 Oct 1958 | Tornado | F2 | $2.5M | — | — | — | County |
Questions and answers
How many tornado events has Stephenson County had?
23 events in the NCEI Storm Events record between 1950 and 2026. Reporting of tornadoes became far more complete after 1996, so early decades undercount.
When was the last recorded tornado event in Stephenson County?
17 Apr 2026 (Tornado, EF2). Records reach NCEI about 120 days after the month ends.
What was the most damaging tornado event recorded in Stephenson County?
The tornado of 8 Oct 1958, with property damage estimated by NCEI at $2.5M.
How does Stephenson County compare with Illinois for tornado?
4.1 events per 100 square miles against 6.6 statewide; the county holds 23 of the state's 3,647 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Tornado hub and the county page.