WATCH: 'Just crazy!' -- Dust devil wreaks havoc along Seattle area shoreline

It was a fairly tranquil Memorial Day Weekend around Seattle, weather-wise, with a noted exception along the shores of Lake Sammamish.

There, a nice afternoon boating on the waters near Marymoor Monday turned quite hair-raising as a dust devil ("lake devil"?) formed and caused quite the commotion as it swirled along the shoreline, tossing around picnic tables and inflatable rafts.

"We were out boating and it was about 65 degrees -- just barely warm enough to be in short-sleeve shirts," said photographer Peter Barnes. "We headed back for dinner and just as we pulled into the dock and let the dogs off the boat, the sun went behind the clouds, the temperature dropped quite a bit, and the wind stated picking up."

And then, a swirl formed on the lake. Barnes, who has 35 years' experience in audio and video production, grabbed his phone and started recording just in time.

"We looked over to our left and saw the water spinning and didn't catch the first part of it as it sat in the corner for 15 seconds," Barnes said. "(We) just started to step out (of the boat) and it was like, 'Woah! Look at that!' "

The dust devil swirled across the water, onto the shoreline and then proceeded to toss everything in its 20-30-foot-wide path into the air, or into the water.

"Oh my God, it's tearing the roof; it's tossing picnic tables into the water -- just crazy," Barnes said.

He said as soon as that orange inflatable boat that was tossed into the air landed three homes down, the dust devil was gone.

"Not a lick of evidence it was there again," he said.

Barnes said it took a good 45 minutes to rummage up and down the beach to collect their belongings -- some of which they had to go into the water to fetch.

"Those picnic benches were made of steel; they weren't light," Barnes said, adding it tore one apart and took two of them to carry another one back out of the water onto shore.

The dust devils are caused when you have hot air suddenly rising from warm ground. As this air rises, it can sometimes create a little vortex of swirling air. They're usually harmless, but can pack a powerful punch of a small area.

"We're pretty happy the dogs got away," Barnes said. "It happened in a flash."