Most lightning bolts do not hit the ground - but the 25 million that do each year in the U.S. injure or kill, on average, about 400 people.

Lightning does tend to hit higher spots - it's a simple matter of electricity seeking the shortest path to the ground. The safest place to be in a thunderstorm is inside a sturdy building. The next safest refuge is in a car, but not because of the rubber tires. Instead, the metal body of the car will conduct the electricity into the ground, so you're relatively safe inside the car as long as the windows are up and you're not touching any metal - and let's face it, there's not much metal inside modern cars. Convertibles and other vehicles that don't have a full metal body are not safe.

As far as gauging when lightning is a threat, the so-called 30-30 rule is useful: if 30 seconds or less passes between seeing lightning and hearing its thunder, the lightning is close enough to be a hazard. And you should wait 30 minutes after seeing the last lightning flash before resuming your normal outdoor activities. Remember this: more than half of all lightning fatalities occur after the thunderstorm has passed.