Lightning Danger

Looking out across the canyon during a storm. A bolt of lightning on the far left hitting the canyon rim on the north side.
Monsoonal thunderstorms move through Arizona from July to September, offering beauty, excitement, and much-needed water, but dangerous and potentially deadly lightning accompanies them. Reduce your risk: learn how to avoid lightning dangers and practice basic safety precautions.
Sepia toned historic photo of multiple lightning strikes. Rim is in silhouette

What is Lightning?

Powerful electric sparks from a thunderstorm cause lightning, which can kill instantly. Lightning can strike two points up to 10 miles (16 km) apart at the same time and whether or not blue sky is visible.

Lightning moves at 90,000 miles (144,841 km) per second with voltage up to one billion volts. A standard household electrical outlet is 120 volts. The lightning flash, or channel, is approximately 4 inches (10 cm) in diameter.

Lightning reaches temperatures five times hotter than the surface of the sun. The surrounding air expands rapidly due to the heat of the bolt's flash and causes thunder, warning us that lightning is present. In Grand Canyon National Park, lightning strikes an average of 25,000 times per year. Enjoy the canyon, but be alert.


How Do I Stay Safe?

Before you travel or hike: Check the weather forecast at visitor centers, campgrounds, or lodges. Arrange activities to minimize your exposure to lightning danger.


Use these guidelines to make a lightning safety plan, and be prepared to follow it.

  • Be aware of the nearest safe structure or vehicle and how long it will take to reach it; learn where emergency phones are located on the trails.
  • Listen for thunder, watch for lightning, and observe the direction of storm movement.
  • Be vigilant of possible flash floods or falling rocks during or after storms.
  • If you find yourself in a dangerous situation with a thunderstorm approaching, take cover.

If your hair stands on end, a strike is looming:

  • Move away from the canyon edge; leave open areas immediately; and avoid rocky outcrops, lone trees, the tallest trees, poles, railings, and bodies of water.
  • Get to a shelter—building, vehicle with the windows closed, or shuttle bus—as quickly as possible.
  • For a shuttle bus, locate a designated bus stop.
  • If camping, wait out the storm in a safe structure or vehicle, not a tent.
  • Do not touch rock walls or any metal on vehicles or structures.

Remember: when thunder roars, go indoors !

An image of a girl crouching with her hands over her ears

NPS / Laura Shultz

What if There is No Shelter?

If you find yourself caught in a thunderstorm with no readily available shelter, be calm and use good judgement.

To reduce your risk:

  • If possible, spread out from other people. Look for lower ground, but avoid areas that may flood. Do not touch metal guard rails.
  • If in an open area, crouch on the balls of your feet with your heels touching, head down, and hands covering ears. Your hands should not touch the ground. Do not lie flat on the ground.
  • Always remember to move away from the canyon edge; leave open areas immediately; and avoid rocky outcrops, lone trees, the tallest trees, poles, railings and standing water.

How do I Maintain a Safe Distance?

Lightning can reach more than 10 miles (16 km) from a cloud and far beyond where rain falls—you are still in a high danger zone even when it is not raining.

  • If you hear thunder, you are at risk of getting struck by lightning. When thunder roars, go indoors When you hear thunder, take shelter.
  • The 30–30 rule - If the sound of thunder follows a lightning flash in 30 seconds or less, seek shelter immediately. Danger continues for 30 minutes after the last lightning or thunder event.
  • Flash to bang calculations Count the seconds between flash of lightning and bang of thunder. Divide number of seconds by 5 to estimate distance from you to where lightning struck in miles (5 seconds = 1 mile). To find distance in kilometers, divide number of seconds by 3 instead of 5. If you are within 6 miles (10 km) of lightning flashes, you are in a high-danger zone. Seek shelter immediately!

Inclement Weather Operations on Hermit Road

  • During summer thunderstorms, or other inclement weather, shuttle bus service will be suspended on Hermit Road.
  • Visitors will not be transported via shuttle bus from the Village Route Transfer Station, westward to viewpoints along Hermit Road.
  • However, shuttle bus drivers along this route will do all they can to either shuttle visitors along Hermit Road east to the Transfer or become standing shelters out along the route.
  • When service is suspended due to inclement weather, shuttle buses with additional capacity will stop anywhere along the Hermit Road it is safe to do so, and pick up visitors.
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Monsoonal thunderstorms move through Arizona offering beauty, excitement, and much-needed water, but dangerous and potentially deadly lightning accompanies them. Reduce your risk and learn how to avoid lightning dangers by practicing basic safety precautions.

A summer storm passes over the canyon.

Additional Lightning Information

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    Last updated: August 3, 2018

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