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One of the hardest hit areas was Napa, where social media users shared video of hail.
Hail in Lake Berryessa today! pic.twitter.com/TMwwxFe7QW— Kendell Momaney (@KendellMomaney) June 12, 2017
Meteorologist Drew Tuma said lightning strikes were reported from Novato all the way to Davis. At least nine strikes were reported in a 15 minute period.
Dime to walnut sized hail was falling in the areas as well as temperatures took a big dip - 25 degrees below normal in some places.
A Caltrans employee tweeted about the unseasonably cold weather from interstate 80. "Please slow down. The cars behind me are going way too fast in these conditions. Enjoy the view, it's the middle of June and it's snowing. That's why I love working on Donner Pass," the employee said.
The sound of thunder also rattled a few nerves.
In Petaluma a resident caught the lightning on video. North Bay residents we talked to found the whole thing amusing.
"My neighbor and I were cracking up because it went from being really sunny to all of a sudden just thunder, lightning, raining, wind. And, we both looked at each other and said, 'what the heck? It's June,'" Petaluma resident Jill McIlvane said.
In other cities, it was the more mundane stuff.
While storms are losing their punch, the threat of lightning is still there. Move indoors immediately if you hear thunder⛈️⛈️ pic.twitter.com/uRp1qfDM52— Drew Tuma (@DrewTumaABC7) June 12, 2017