Significant October Tornadoes in the United States

Compared to the drop in overall tornadoes in October from September, the rate of decrease among strong or significant (F2/EF-2+) tornadoes is less pronounced, and there is actually a slight bump in the current climatological average. As with August, and the cold-season months to come, October is mostly a “feast or famine” time of year for strong tornadoes. Though not numerous, these are the tornadoes which cause trouble and are worth a deeper examination.

October Significant Tornado Climatology (1950-2011)

Total significant tornadoes: 451
October high: 23 (1974)
October low: 0 (1952, 1982, 1987, 2003, 2008)
1991-2010 climatological average: 6.5
1991-2010 median: 5

Texas holds a notable lead in October when it comes to strong tornadoes, even given its size. It is also a substantial increase in strong tornadoes from month to month, with 97 in October compared to 53 in September. Oklahoma, another southern Plains state, also shows a less substantial increase in significant tornado activity compared to September. Southern states are preferred throughout, but that idea also bleeds north into the Midwest and Tennessee and Ohio valleys. October’s most prolific tornado outbreaks, like that which produced 62 tornadoes without a six hour break on 10/26-27/2010, usually occur over areas east of the Plains.

Isolating F3/EF-3 tornadoes gives us a top five list including Texas, Kansas, Oklahoma, Indiana and Louisiana. For the most part, tornadoes of this level, or higher, are fairly uncommon for October and tend to come in clumps. So far in the 2000s, only three years have featured an October tornado of F3/EF-3 or higher (2001, 2007, 2010). 2001 was particularly notable of that group with eight such tornadoes on four different days from Oklahoma to Ohio.

There’s not much to talk about when it comes to violent (F4/EF-4+) tornadoes in October, and that’s a good thing given what they tend to cause. While there is no real pattern to this level of data, it’s at least worth mentioning Connecticut. The October 3, 1979 F4 that hit Windsor Locks is the most recent violent tornado the U.S. has seen in October and one of two tornadoes of that strength to hit the state. The only F5 of the month hit Belmond, Iowa on October 14, 1966.

U.S. Tornado Climatology by Month

All: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
Significant: Jan | Feb | Mar | Apr| May | Jun | Jul | Aug | Sep | Oct | Nov | Dec

SPC tornado data obtained at the Tornado History Project. Images can be selected for larger versions. Get updates about U.S. Tornadoes on Twitter and Facebook. Official 2012 data will be available during spring 2013.