What Causes Thunder So Loud It Sounds Like An Explosion

The bolt of lightning touched down in Beaverton  just east of Highway 217 by the Home Depot and Target stores.

An instant later there was thunder so loud people called our newsroom saying something had exploded.

 Some called 9-1-1, sure their houses took a direct hit from lightning (they did not) and car alarms suddenly went off in neighborhoods around that part of the Portland metro area.

Thunder is powerful stuff. And it starts with lightning, every single time. In this case the lightning was seen from Sherwood to Clackamas and the thunder slammed Raleigh Hills, Beaverton, Multnomah Village and other parts of SW.

How Lightning Causes Thunder

The image here shows the start: a lightning bolt can be up to 50,000 degrees Fahrenheit. It suddenly heats the air to as much as 18,000 degrees and that air next to the bolt explodes out (and eventually cools and races back in to some degree)  This exploding (expanding) and contracting air creates the sound we know as thunder.

By the way, you can tell how far lightning is from you by counting as soon as you see the flash. One-one-thousand, two-one-thousand and so on. Every five seconds is a mile of distance. So if you count to five before hearing thunder, the lightning is one mile away. If you count to ten, the lightning is two miles away.You should wait at least 20 minutes after the last thunder you hear or lightning you see before heading out again.

In this case–if you were lucky (in weather guy terms) or unlucky (the way everyone else sees it) enough to be in Beaverton it was flash-boom…just that fast! The lightning was right on top of you!


  1. says

    Great article Bruce…. Back when I was a senior in high school, early early
    ’60′s I walked up behind my house up on a newly logged ridge where there was a spar pole… in those days they used a large tall straight tree that they cut all the limbs off the tree and used it for logging. I walked past the spar pole and was about 100 yards to the east of it when I saw out the corner of my eye an 8-10 foot ball of very bright light on the top side of the spar pole.
    The lightning and the boom of thunder was all at the same time…
    I don’t remember if it knocked me down or I got scared and fell down.. probably what happened… ha…. I got up and ran back past the spar pole. The lightning had knocked 30 feet off of the spar pole… after I got home I couldn’t hear for a half hour after I got home.

    This was just behind Rockaway Beach…

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