Avoid hilltops, open spaces, wire fences, metal clotheslines, exposed sheds, and any electrically conductive elevated objects. 

If you do take shelter from lightning in a cave, ditch or canyon during a thunderstorm, watch out for flash flooding! Sometimes a storm can drop enough rain in a short period of time that it makes ditches or canyons into miniature rivers, or fills caves with rainwater. If you think that your shelter has a chance or a history of flooding, find another shelter immediately.