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.
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 !
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.
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.
Lightning Safety at Grand Canyon (Audio Podcast 05m:29s)
Summer thunderstorms (July – September) provide beauty, excitement, and much needed water to Grand Canyon, but they also bring risk. Dangerous, potentially deadly, lightning accompanies thunderstorms. Practicing basic safety precautions can help you reduce risk.
Greetings once again from Grand Canyon National Park’s Backcountry Information Center Podcast! This is Ranger Andrea bringing you words from the wise about lightning safety at Grand Canyon.
Have you ever stood outside during a thunderstorm and had your hair stand on end or felt sharp prickles on your skin? If you have had this happen and are listening to this podcast you are one lucky person! Thunderstorms create an electrical charge in the air which is ultimately released by a lightning strike. If you have experienced the skin prickles or hair-raising, an electrical charge was building where you were standing which means lightning had a high probability of striking in that very spot. I hope you left the area and found cover!
The Grand Canyon region experiences a monsoon season each summer that typically starts in early July and lasts into September. These storms bring the much needed rain that the dry desert landscape requires to flourish. However, they also bring strong thunderstorms that produce lightning, a powerful force of electricity that reaches temperatures of 54,000 degrees Fahrenheit and can travel upwards of ten miles from its parent thundercloud. For this reason, it is important to know how close a thunderstorm actually is and when to take cover.
An easy way to know the distance of a thunderstorm from your location is to count the number of seconds between the lightning strike and the resulting thunder. Dividing that number by five gives you the number of miles between you and the bolt of lightning. For example, if you count ten seconds between the lightning strike and the thunder, you are approximately two miles from the lightning itself. To find the distance of lightning in kilometers, divide the number of seconds by three instead of five. If you are within six miles (or thirty seconds) of the lightning, you are in the “high danger zone” and should seek cover from the storm. Be aware, however, that high danger from lightning may continue for as much as thirty minutes after the last noticeable lightning strike or thunderclap. If you are unsure how far away lightning is, just remember “If you see it, flee it! If you hear it, clear it!”
If you see a thunderstorm building in the distance while standing on the canyon’s rim or hiking its backcountry, a few simple precautions should be taken to avoid injury by lightning. If you are in an established area such as parts of the rim or a developed campground, always be aware of the location of the nearest structure and know how long it will take you to get there. Keep in mind that the nearest structure to you may be your vehicle or a shuttle bus if on the rim. If lightning begins to strike (or you hear thunder, a product of lightning), take shelter in the structure, being sure to avoid metal surfaces and making sure your windows are rolled up if inside a vehicle. The most common mistakes visitors to Grand Canyon make during thunderstorms is not avoiding the rim or neglecting to find proper shelter.
Backcountry travelers who encounter thunderstorms in the canyon do not typically have a structure to use as a safe haven. These hikers cannot eliminate the risks associated with thunderstorms and lightning, but with proper action can reduce their risks. Hikers should always be aware of the surroundings and be mindful of when thunderstorms are or will be present, noting the location of the nearest place where shelter may be taken and making a plan to get there before the storm hits. When camping, you should not use your tent as refuge during a thunderstorm, and you should avoid open areas, rocky outcrops, lone trees, bodies of water, and stands of trees which are taller than surrounding trees. If any of these scenarios are unavoidable, hikers should spread out from each other, crouch down onto the balls of their feet keeping their heels touching, lower their head, cover their ears with their hands and place an insulated sleeping pad under their feet. This creates a smaller target and reduces the likelihood of injury from a lightning strike. If you find yourself hiking in a wooded area along the rim during a thunderstorm, find a small group of trees that are surrounded by taller trees and take refuge there. Finally, metal frame backpacks should be removed and avoided while lightning is present.
Although lightning strikes along the Colorado River are rare, proper precautions should still be taken during thunderstorms to avoid lightning-related injuries. River runners should get off the water while in the high danger zone of thunderstorms, avoid cave entrances and tall trees, and assume the lightning position described earlier if stuck in an open space.
Whether on the rim, hiking Grand Canyon’s backcountry, or rafting the Colorado River, you should always be aware of your surroundings, and know when thunderstorms may pose a threat to you and your companions. Know the weather forecast and check with Rangers for the most up-to-date weather information to find out if lightning has the potential to put you in the “high danger zone.” Finally, always remember the foolproof phrase that will help save you from the risks associate with lightning: “If you see it, flee it! If you hear it, clear it!”
