There's a good reason why spring afternoons are most closely associated with tornadoes: That's when they typically happen. What's less familiar to us is tornadoes that strike in winter and at night — and they may be even more dangerous at those times.
In the United States, the three quietest months for tornadoes are December, January and February, which makes sense because cold air is more stable than warm air. Still, this period sees an average of 114 tornadoes each year, mainly in the Southeast [source: Erdman]. Though somewhat rare, these tornadoes may actually be more dangerous because they move faster, thanks to tornado-producing winds in the upper atmosphere that accelerate in winter. This gives residents in the storm's path even less time to take cover [source: Drye].
Night, like winter, isn't primetime for tornado formation: Only 27 percent occur in the hours between sunset and sunrise. But 39 percent of fatalities happen at night, and tornadoes that happen between midnight and sunrise are 2.5 times as likely to cause fatalities [source: Walker et al.]. How could this be? The main reason, as you might've guessed, is because most people are sleeping at night. They're much less likely to hear warning sirens or alerts on their televisions or radios. Luckily, there's an app for that. The American Red Cross offers a program for your phone that will sound an alarm if a tornado strike is likely. A good, old-fashioned weather radio will do the same thing.