Lightning Safety
How to protect yourself from lightning during thunderstorms.
Last revised
Key takeaways
- Rule of thumb: when thunder roars, go indoors
- Safe shelter: an enclosed building with plumbing and wiring, or a hard-topped metal vehicle with windows closed
- Most useful single change: Check the forecast before outdoor activities and plan where you will shelter.
- Commonest mistake: Sheltering under a tree.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
No place outdoors is safe when thunder can be heard, and many lightning injuries happen to people who were close to shelter.
The numbers, in one place
| Measure | Figure |
|---|---|
| Rule of thumb | when thunder roars, go indoors |
| Safe shelter | an enclosed building with plumbing and wiring, or a hard-topped metal vehicle with windows closed |
| Not safe | open shelters, tents, picnic pavilions, under trees |
| Wait time | stay inside until 30 minutes after the last thunder |
| Victims | people struck by lightning do not carry an electric charge and are safe to touch |
What helps
- Check the forecast before outdoor activities and plan where you will shelter
- Head indoors as soon as you hear thunder
- Stay off corded phones and away from plumbing and electrical equipment during a storm
- Learn CPR so you can help someone who has been struck
What to avoid
- Sheltering under a tree
- Staying in or near water during a thunderstorm
- Returning outside as soon as the rain stops
In depth
Lightning is a giant electrical discharge between a storm cloud and the ground or within clouds. It can strike miles away from the storm itself, sometimes appearing to come out of a clear sky, which is why there is no safe place outdoors once you can hear thunder. Most lightning victims are not caught by surprise in the middle of a storm; many are struck before the rain arrives or after it ends, when they think the danger has passed.
Only a small share of injuries come from a direct strike. More often, the current spreads through the ground and up into a person nearby, jumps from a tree or object to someone standing close to it, or travels through wires, pipes or metal fences. This is why sheltering under a tree or in an open pavilion is unsafe: they attract the strike and the current can spread to anyone underneath or nearby.
Lightning's biggest immediate danger is to the heart and breathing. A strike can stop the heart and the breathing center in the brain. The heart sometimes restarts on its own while breathing does not, so rescue breaths and CPR can save lives. Most people survive lightning strikes, but many live with long-term effects such as memory problems, chronic pain, hearing loss or mood changes, which may not be obvious at first.
Signs and symptoms
- Thunder you can hear, which means lightning is close enough to strike you
- Darkening skies, rising wind and a building thunderhead cloud
- Hair standing on end or a tingling feeling on the skin, a sign a strike may be imminent
- In someone struck: unconsciousness, confusion or not breathing
- Fern-like red patterns on the skin, burns, or temporary paralysis of the legs or arms
- Ringing ears, hearing loss or vision problems after a strike
Causes and risk factors
- Being outdoors during thunderstorms, especially in open areas
- Activities such as fishing, boating, camping, hiking, golf and field sports
- Outdoor work in construction, farming and landscaping
- Being near tall, isolated objects such as trees, poles or towers
- Contact with water, plumbing, wired phones or electrical equipment during a storm
- Waiting too long to seek shelter, or returning outside too soon
How it is checked
Anyone struck by lightning should be checked in an emergency room, even if they seem fine, because some injuries are hidden. Doctors check the heart with an electrocardiogram and blood tests, look for burns and injuries from being thrown, and examine the eyes and ears. A person may have had their eardrums ruptured or developed injuries to the spine or head.
Some effects only appear later. Cataracts can develop months after a strike, and problems with memory, concentration, sleep, pain or mood can emerge or persist long term. Follow-up with your primary care doctor, and referrals to eye, hearing, neurology or mental health specialists, can help identify and manage these.
Related topics
- CPR and Defibrillation: What the Evidence Actually Says (Emergency Care)
- Hearing and the Brain: Sorting the Evidence From the Noise (Brain Health)
- What the Guidance Really Says About Opioid Overdose and Naloxone (Substance Use and Recovery)
- What the Guidance Really Says About Air Pollution and the AQI (Environmental Health)
Where to go next
- Popular Beliefs About Lightning Safety, and What Is Actually Published
- Lightning Safety: A Beginner-Friendly Start
- Weather Safety: The Complete Guide
- What the Guidance Really Says About Flood Water Safety
- What the Guidance Really Says About Older Adults and Extreme Weather
When to get help
Call 911 right away for anyone struck by lightning. If they are not breathing or have no pulse, start CPR and use an AED if one is available.
Where this comes from
- CDC — Lightning Safety
- American Red Cross — Thunderstorm Safety
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.