If caught in a thunderstorm outdoors, get into a hard-topped vehicle or building; avoid ridges, lone trees, water surfaces, and metal objects

Cost: No monetary cost. The downside is that your trip gets interrupted for at least half an hour. The real challenge is actually turning back when the thunder is still far away.
In plain terms: There is no safe spot outdoors during a thunderstorm. You must get into a hard-topped vehicle or building; convertibles and motorcycles do not qualify. Tents, gazebos, areas under trees, or rocky outcrops also do not count as shelter. Stay away from open areas, mountain ridges and peaks, isolated tall trees, water surfaces, and metal railings or poles. If a group cannot all fit together, spread out rather than huddling close. Begin retreating the moment you hear thunder; it is only safe to leave 30 minutes after the final clap of thunder.
Benefit: There is no safe spot outdoors during a thunderstorm. It is only safe to leave 30 minutes after the final clap of thunder.
Evidence grade: B
Sources:美国国家气象局. 户外雷电安全：「There is no safe place outside when thunderstorms are in the area」「Avoid open fields, the top of a hill or a ridge top. Stay away from tall, isolated trees or other tall objects」「Stay away from water, wet items, such as ropes, and metal objects, such as fences and poles」；实在走不了时「If you are in a group, spread out to avoid the current traveling between group members」；恢复活动「Wait 30 minutes until after the last rumble of thunder」. https://www.weather.gov/safety/lightning-outdoors
Notes: Tents, gazebos, areas under trees, and rocky outcrops do not qualify as shelters. Hard-topped cars do count, but convertibles and motorcycles do not. Start retreating the instant you hear thunder; do not wait until rain begins to fall.