Why Lightning Safety Matters on the Trail
Caught in a thunderstorm mid-hike? Seeking shelter under the nearest tree might seem like a good idea—but it’s one of the most dangerous choices. Instead, understanding how to calculate a safe distance from tall objects using simple math can minimize your risk of a lightning strike.
By applying tree height ratios, hikers can determine how far away they need to be to reduce the danger of ground currents and secondary strikes.
How to Calculate a Safe Distance from Trees
- Follow the 2:1 Rule
- A safe distance from a tree is at least twice its height.
- If a tree is 20 feet tall, stay at least 40 feet away.
- Using Angle Approximation for Quick Field Estimation
- Stand at a distance and extend your arm, using your thumb or trekking pole to “measure” the tree height against your line of sight.
- Walk backward until the top of the tree aligns with a 45-degree angle from your position. This is approximately twice the tree’s height, ensuring safer positioning.
- Avoid Grouping Too Close
- Ground currents from a lightning strike can spread outward, affecting hikers within a radius equal to tree height.
- Spreading out by at least 50 feet per person reduces risk of multiple injuries.
Additional Lightning Safety Tips for Hikers
- Descend from Exposed Areas: Avoid ridgelines, peaks, and open fields.
- Assume the Lightning Position: If caught in a storm, crouch low with feet close together to minimize ground contact.
- Count Flash-to-Bang Time: If thunder follows lightning within 30 seconds or less, seek shelter immediately.
By using basic math and distance estimation techniques, hikers can make smarter, faster decisions in lightning-prone areas. Next time a storm rolls in, apply these calculations to stay safe and grounded.