In the southern USA tornadoes tend to form most frequently in the early spring, while in the northern USA they are most common in summer. For example, in Iowa most tornadoes occur between April and September, with April and May being the most dangerous months. Most tornadoes occur in the American Midwest, between the Appalachian Mountains and the Rockies. However, tornadoes can occur in all American states. In 1999 there was a hurricane in Salt Lake City, Utah, which was regarded as being a highly usual event.
Most tornadoes move from southwest to northeast.
Most tornadoes occur in the late afternoon or early evening. A tornado warning means that a tornado has been spotted and you should observe the safety hints listed below. A tornado watch means that weather conditions are right for the formation of tornadoes. You should listen to local radio and television stations for up to date weather information, if possible using a battery operated set. Officially this refers to a hurricane or a typhoon.