An outbreak means many tornadoes in a short time over a wide area. Keep a way to receive warnings indoors on any day with a tornado watch.
| Outbreak | Dates | Count (SPC) | Note |
|---|---|---|---|
| April 2011 outbreak | April 27 to 28, 2011 | 175 tornadoes in 24 hours | EF0: 59, EF1: 65, EF2: 20, EF3: 16, EF4: 11, EF5: 4 |
| Super Outbreak | April 3 to 4, 1974 | 147 known tornadoes | Most F5 tornadoes in one day: seven |
| Hurricane Beulah | 1967 | 115 tornadoes in 24 hours | The only other 24-hour outbreak above 100 |
What counts as an outbreak
The Storm Prediction Center says the answer depends on how an outbreak is bracketed, and there is no universally accepted definition. It typically uses the 24-hour convective day starting and ending at 12 UTC, which is 7 a.m. CDT.
The biggest outbreaks
By that count the greatest swarm was 175 tornadoes on April 27 and 28, 2011, with a damage-rating breakdown of EF0: 59, EF1: 65, EF2: 20, EF3: 16, EF4: 11 and EF5: 4. It supplanted the Super Outbreak of 147 known U.S. tornadoes on April 3 and 4, 1974, which still holds the record for the most F5 tornadoes in a single day, with seven. Only one other 24-hour outbreak produced over 100 confirmed tornadoes: Hurricane Beulah in 1967, with 115. Hurricane Ivan in 2004 produced 118 tornadoes in three days, but in separate daily cycles.
By calendar day and by month
By calendar day, April 27, 2011 also holds the modern record with 209 tornadoes confirmed at the time of the SPC page. The month with the most tornadoes since 1950 was April 2011, with 817.
This is not a full list
The table here covers only the record outbreaks the SPC cites. For single tornadoes see our guide to the strongest, deadliest and biggest tornadoes, and for the state-by-state picture see tornadoes by state.
Staying safe
On a day with a tornado watch, keep more than one way to get warnings indoors and know where you would shelter. See our tornado safety guide.
Check your own location
See current official alerts and the impact for your ZIP code.
Common questions
What is a tornado outbreak?
A tornado outbreak is a swarm of many tornadoes in a short period. The Storm Prediction Center says there is no universally accepted definition and typically uses the 24-hour convective day starting at 12 UTC.
What was the biggest tornado outbreak?
By the SPC 24-hour count, April 27 and 28, 2011, with 175 tornadoes. By calendar day, April 27, 2011 has the modern record, with 209 tornadoes confirmed at the time of the SPC page.
What month had the most tornadoes?
April 2011, with 817 tornadoes in SPC data since 1950.
Sources
Reviewed by the Storm Incoming editorial team on October 27, 2026. Follow local emergency officials if their instructions differ.