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What is Dry Lightning?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Dry lightning is lighting which strikes without any accompanying rain. Obviously, “dry” lightning is a bit redundant, since lightning is not usually particularly wet, but the term has caught on because it is so descriptive. The Western region of the United States is famous for its dry lightning, which sparks hundreds of wildfires each year, some of which grow to be dangerously large.

In a normal thunderstorm, lightning strikes while rain falls from the stormclouds, usually accompanied by the sound of thunder. When the lightning hits the ground, it may cause a spark of flame, but the rain which comes down with the lightning puts the fire out before it has a chance to spread. In a dry storm, rain is produced, but it never reaches the ground.

Dry lightning causes hundreds of wildfires each year.
Dry lightning causes hundreds of wildfires each year.

In many Western states, storms tend to form extremely high, which means that the rain may pass through a zone of warm air on its way to the ground. The dry, warm air causes the rain to evaporate, returning the cloud and fueling the storm while also ensuring that it does not hit the ground to put out fires caused by lightning strikes. Such storms are also often accompanied by dry microbursts, gusts of cold air which rush down from the clouds and spread rapidly when they hit the ground, causing gusting winds along the surface of the Earth.

So-called dry lightning is common in western areas of the U.S.
So-called dry lightning is common in western areas of the U.S.

As one might imagine, dry lightning and dry microbursts can be a recipe for disaster. Even as the lightning strikes the ground to spark a fire, a gust of wind can push the margins of the fire, causing it to spread rapidly. In areas where groundcover and forests are not well managed, explosive fire conditions can emerge during dry lightning storms, quickly covering ground and sometimes even trapping firefighting personnel.

Generally, the risk of dry lightning can be predicted in advance, with meteorologists using existing data to predict dry thunderstorms. In these instances, warnings may be issued to alert people to the fire risk, and the risk of unpredictable storms leads many communities to encourage citizens to create firebreaks around their homes by keeping ground cover down, and grass tightly trimmed. In areas where dry lightning is especially common, building codes may also include built-in fire protections, to make structure fires less likely.

Frequently Asked Questions

What exactly is dry lightning?

Dry lightning refers to a thunderstorm where the rain evaporates before reaching the ground, typically due to hot, dry air. This phenomenon is particularly common in arid regions and can lead to wildfires, as the lightning can ignite dry vegetation without the accompanying rain to dampen the potential fuel.

How does dry lightning differ from regular lightning?

Unlike regular lightning, which occurs during wet thunderstorms where rain reaches the ground, dry lightning strikes within a dry atmosphere. The key difference lies in the precipitation: with dry lightning, the raindrops evaporate in mid-air, never moistening the earth, whereas regular lightning is accompanied by rainfall that can help mitigate fire risks.

Why is dry lightning considered a wildfire hazard?

Dry lightning is a significant wildfire hazard because it can ignite fires in the absence of rain. According to the National Weather Service, lightning causes an average of 9,000 fires each year in the United States. Dry lightning strikes are particularly dangerous as they provide an ignition source without the mitigating effect of rain to extinguish small fires.

Can dry lightning occur in any climate?

While dry lightning can occur in various climates, it is most prevalent in arid and semi-arid regions. These areas are characterized by conditions that favor the evaporation of rain before it hits the ground, such as high temperatures and low humidity levels. However, dry lightning can also happen during heatwaves in typically wetter climates.

Is there a specific season when dry lightning is more common?

Dry lightning is more common during the warmer months when conditions are likely to be hotter and drier. In the western United States, for instance, the summer season is particularly prone to dry lightning storms, which coincide with the peak of wildfire season, exacerbating the risk of fires spreading rapidly.

How can we protect ourselves and our property from dry lightning?

To protect against dry lightning, it's crucial to maintain a defensible space around your property by clearing away dry vegetation and other potential fuels. Installing lightning rods can also help. During dry lightning storms, stay indoors, avoid tall structures or open areas, and follow local fire safety guidelines to minimize risk.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

anon286713

I found this to be very interesting as I live in Missouri and have seen dry lightning. I never understood it because there was no rain involved. It has occurred several times this last couple of weeks. It this also what it called a bolt out of the blue?

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    • Dry lightning causes hundreds of wildfires each year.
      By: Paulo M.F. Pires
      Dry lightning causes hundreds of wildfires each year.
    • So-called dry lightning is common in western areas of the U.S.
      By: El Gaucho
      So-called dry lightning is common in western areas of the U.S.