May 31
- 1985 – An unusual and catastrophic tornado outbreak produced violent tornadoes across parts of Ontario, Ohio, Pennsylvania, and New York, killing 90 people. An F5 tornado devastated portions of Niles, Ohio and Wheatland, Pennsylvania, killing 18 people. Other hard-hit communities included Atlantic, Pennsylvania, Albion, Pennsylvania, and Barrie, Ontario. One tornado in Moshannon State Forest was 2.2 miles (3.5 km) wide, one of the widest on record.
- 2013 – The widest tornado ever recorded reached a maximum width of 2.6 mi (4.2 km) near El Reno, Oklahoma and had radar-indicated wind speeds of 302 mph (486 km/h). Among the eight people killed were four storm chasers, including Tim Samaras. This was the first known case of a tornado killing storm chasers.