US tornado season is centered on April, May, and June, when roughly 60% of all US tornadoes occur. But the peak timing varies dramatically by region: the Great Plains peak in May, the Deep South peaks earlier and has a strong secondary peak in November, and Florida is essentially year-round.
| Month | Avg tornadoes | Share of year |
|---|---|---|
| January | ~35 | 3% |
| February | ~40 | 3% |
| March | ~85 | 7% |
| April | ~180 | 15% |
| May | ~270 | 22% |
| June | ~240 | 20% |
| July | ~130 | 11% |
| August | ~85 | 7% |
| September | ~55 | 4% |
| October | ~50 | 4% |
| November | ~50 | 4% |
| December | ~30 | 2% |
Peak season: April through June, with May generally the busiest month. Activity ramps quickly in April as Gulf moisture surges north and the jet stream is still active. May and early June combine peak moisture with strong upper-level winds. By July, the jet stream retreats north and tornado activity drops sharply. A weaker secondary peak in September–October is common in southern Kansas and Oklahoma.
Bimodal season: primary peak March–April, secondary peak November–December. The March–April peak is often more intense and deadlier than the Great Plains peak because Dixie Alley tornadoes are more likely to occur at night, in rain-wrapped conditions, and over densely populated areas with high mobile-home concentrations. The Nov–Dec peak is unique to Dixie Alley and includes some of the deadliest events in modern history (e.g., April 27, 2011 and December 10, 2021 Quad-State).
Peak season: April through July. Peak intensity typically runs a month or two later than Tornado Alley, as warm season conditions arrive later. The Ohio Valley is prone to violent (EF3+) tornadoes when the jet stream lingers in June and July — Xenia 1974 is the reference case.
Florida has the highest tornado density per square mile after Kansas and Oklahoma but few violent events. Peak activity is June through September, driven by tropical systems and sea-breeze thunderstorms. Hurricanes routinely produce tornadoes as they make landfall.
Peak season: June through August. Warm-season heating and moisture arrive latest here. Late-summer supercells over the Dakotas and Minnesota can be exceptionally photogenic and are heavily targeted by storm chasers.
Peak season: June and July. Colorado east of Denver averages a healthy number of tornadoes per year, though mostly weak (EF0–EF2). Higher terrain west of the plains sees very few.
Nationally, tornadoes are most common between 3 PM and 9 PM local time — the hours when daytime heating maximizes instability. In the Great Plains, roughly 70% of tornadoes touch down during this window.
Dixie Alley is different. Roughly 45% of Southeast tornadoes occur at night — nearly twice the national rate. Ashley (2007) showed nocturnal tornadoes are 2.5× more likely to kill because people are asleep and warning systems are less effective indoors.
Tornadoes can strike any month of the year and anywhere in the US, but violent (EF3+) tornadoes outside the March–July window are rare. Notable exceptions:
Research since 2018 (Gensini & Brooks, others) shows the highest tornado frequency is shifting east from the traditional Great Plains core, and the peak of tornado activity is shifting earlier — into March and April rather than May and June. The exact drivers are still debated but likely include warmer Gulf sea-surface temperatures and changes in jet-stream behavior. If you live in Dixie Alley, plan for tornado season to start no later than February 15.
→ Simulate a peak-season tornado