Does El Nino cause tornadoes?
No. Neither does La Nina. Both are major changes in sea surface temperature in the tropical Pacific which occur over the span of months. U.S. tornadoes happen thousands of miles away on the order of seconds and minutes. El Nino does adjust large-scale weather patterns. But between that large scale and tornadoes, there are way too many variables to say conclusively what role El Nino (or La Nina) has in changing tornado risk; and it certainly does not directly cause tornadoes. A few studies have shown some loose associations between La Nina years and regional trends in tornado numbers from year to year; but that still doesn’t prove cause and effect. Weak associations by year or season may be as close as the ENSO-to-tornado connection can get — because there are so many things on the scales of states, counties and individual thunderstorms which can affect tornado formation. For more detailed information, see The Relationship between El Nino, La Nina and United States Tornado Activity, a
