Tornadoes happen in the summer every year.
Since 1950 there have been six or so tornadoes in Los Angeles according to SPC records. This works out to an average of about one every 10 years.
As of July 2016, tornadoes have killed 1,054 people in the U.S. in the past 10 years. More than half of those deaths occurred in 2011, which was an exceptionally violent year for tornadoes.
In the past 10 years tornadoes at least 1402 people have been killed by tornadoes, including 1089 in the United States.
Year Without a Summer happened on 1815-04-10.
See the link below for Alabama statistics from the National Weather Service.
As of mid December 2013 there have been 12,800 officially documented tornadoes in the United States in the past 10 years. Note that figures for several months in 2013 are still preliminary.
They would merge into a single although much larger tornado
Moore, Oklahoma has had 6 tornadoes in the past 10 years: 3 on May 10, 2010; 1 on May 24, 2011; 1 on May 20, 2013; and 1 on May 31, 2013
Tornadoes do occur in Virginia, but they are not as common as in the central United States. Virginia typically experiences about 10-20 tornadoes per year, with peak activity in the spring and early summer months. It is important for residents to be prepared and have a plan in case a tornado does occur.
Yes, tornadoes have been recorded in Montana. While they are less common compared to the central plains of the United States, tornadoes do occur in Montana, especially during spring and summer months. The state typically experiences around 4-6 tornadoes per year.
In the past 10 years at least 1420 people have been killed by tornadoes worldwide, with most of those reported deaths occurring in the U.S. The real worldwide figure is likely higher as data is incomplete or missing for some countries.
How long a tornado lasts can vary widely. The average tornado lasts about 10 minutes. But tornadoes have been known to last as little as 10 seconds and as long as 3.5 hours. Not many tornadoes last more than 30 minutes. As to when they occur, tornadoes can form at any time of day or night, but are most common in the later afternoon and early evening. Similarly, tornadoes can occur at any time of year, but happen primarily in the spring.