 1,100 tornadoes were reported region-wide in May, from Texas to Minnesota and from West Virginia to Georgia. That's more than twice the 30-year average. One of the fiercest killed five people and injured dozens in rural Greenfield, Iowa. ISU severe weather meteorologist William Gallus says extreme heat from a changing climate has increased ocean temperatures and is one contributing factor to this year's storms. Mexico and Texas were having record high temperatures.