Significant June Tornadoes in the United States

Significant F2/EF-2+ tornadoes have historically made up just shy of 16 percent of all June tornadoes throughout the modern record stretching from 1950-2011. That’s the smallest ratio of strong tornadoes to all tornadoes in the months examined (Feb-June) here thus far. However, these storms remain those which are costliest to life and property.

June Significant Tornado Stats (1950-2011)

Total significant tornadoes: 1,708
June high: 62 (1990)
June low: 3 (2006)
1991-2010 average: 17.1

There is a notable downward trend in significant tornadoes compared to May, though there are also a number of formidable years, with six of them having 50 or more, and many others above the May average of 30.

As seen in the June map of tornado strikes, by June, tornado activity has migrated north and west through the Plains compared to previous months. Significant tornado activity largely mirrors these trends, though we see certain change-ups like Colorado dropping out of the top 5 overall and Iowa jumping into it for F2/EF-2+ counts.

Interestingly, Iowa sees about 23 percent of all tornadoes rated as strong in June to Colorado’s quite paltry 7 percent. Part of this is due to the fact that weaker land spouts (generally non-supercell tornadoes) tend to frequent Colorado in the summer, while Iowa often sits in a strongly capped but very volatile environment of high heat and humidity just waiting for a trigger.

Like all active month’s it’s part of, Texas’s size-induced lead in overall and significant tornadoes gets wiped as one examines the steps up toward the stronger of the strong twisters. Kansas has been home to the most F3/EF-3 tornadoes over the period, and Texas falls to fourth behind Nebraska and South Dakota.

Violent tornadoes make up a smaller portion of all tornadoes compared to earlier months as the strong jet stream energy often needed to spawn them continues to weaken heading into the heart of summer. Kansas again leads the pack for F4/-EF4s. It’s perhaps again somewhat notable that Colorado has not had a verified violent tornado in June, despite June being the peak of tornado season there.

Nine tornadoes in June have reached the ultimate high end of F5/EF-5, and this is the end of peak season for this monster class, with only another five observed through December. The June list is headed by the upper Midwestern states of Minnesota, Iowa and Wisconsin. An F5 last touched down in June on the 8th in 1992 across southwestern Minnesota.

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.