We’ve all heard the reality check before: “You have a better chance of being struck by lightning than winning the lottery.”

To most of us, the odds of being struck by lightning, “1 in a million,” are a convenient measuring rod for all things unlikely. Whether it’s winning the lottery or dying in a plane crash, if something is less likely to happen to you than being struck by lightning, then, as the logic goes, it’s probably not worth holding your breath for or worrying about very much (discussions along these very lines can be found here and here).

Lightning Odds…Not So Simple…

The odds of being struck by lightning, however, are not as simple as we would have them to be. The answer to the question, “What are the odds of being struck by lightning?” is actually, “It depends.”

What’s particularly noteworthy is that depending on which state you’re in within the United States, your odds of being struck by lightning this year can be much higher or much lower than that 1 in a million figure mentioned above. For example, based on lightning data (courtesy StruckByLightning.org) and U.S. Census Bureau population estimates for 2011 presented in the map below, if you live in Montana, your odds of being struck by lightning are roughly 1 in 249,550, considerably higher than the the national average of 1 in a million. Towards the other end of the spectrum, in California, your odds of being struck by lightning are far lower at 1 in 7,538,382.

Clearly, the odds of being struck by lightning are not the same for everyone, everywhere, but why?  We face varying odds of being struck by lightning because of a few key factors. These essentially location-specific factors include: Cloud-to-ground lightning density rates, population size, indoor vs. outdoor activity setting and safety adherence.

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U.S. Cloud-to-Ground Lightning Density

This Vaisala National Lightning Detection Network (NLDN) map shows the average annual lightning flash density within the continental U.S. from 1997-2011.

In terms of cloud-to-ground lightning averages, Florida ranks highest, with an average of 1,414,284 flashes per year (24.7 flashes per square mile). Historically, Florida has also experienced the highest lightning number of lightning deaths in the United States, with 425 deaths occurring there from 1950-2003. Washington has the lowest cloud-to-ground lightning averages, 20,510 flashes per year (0.3 flashes per square mile).

Population

State population plays in a key role in determining your odds of being struck by lightning. Florida tops all the states both in terms of cloud-to-ground lightning density and the number of lightning casualties reported annually (31 in 2011), but because of Florida’s population size, an estimated 19,057,542 for 2011, the odds of being struck by lightning there were 1 in 614,759. These odds are lower  than Montana’s 1 in 249,550, even though Montana had only 4 lightning casualties, because in comparison, Montana’s estimated 2011 population was much smaller: 998,199.

Indoor vs. Outdoor

Simply put, more time spent outdoors increases the odds of being struck by lightning. In places where people work and engage in more activities outdoors, the odds of being struck by lightning tend to be higher.

Did You Know?

As discussed in a USA Today article by Doyle Rice, there has been an overall decline in lightning fatalities in the U.S. since 1940, largely due to the impact of public education efforts and increased public recognition of the value of following safety principles.

Lightning Safety

The U.S. National Weather Service cautions that when there is a thunderstorm in the area, no place outside that is safe. Moreover, if you can hear thunder, that means that lightning is, in fact, close enough to strike you. If you are outdoors when you hear thunder, seek safe shelter. In short, when it comes to lightning, the message that lightning experts and organizations regard as being the most crucial is to go indoors when there is a thunderstorm in the area. Thus, the National Weather Service, StruckByLighting.org and others have worked hard to get the simple message out: “When Thunder Roars, Go Indoors!”

Featured Image Credit: Brilhasti1/Flickr