The comparison only really works for the West coast though. The East coast is dominated by continental climate carried over from the interior by the prevailing winds. Meanwhile Europe is surrounded by water on three sides, plus the Baltic and North Sea in the middle. Just having this much water nearby (plus prevailing winds coming from an ocean) moderates temperature swings a lot

Yeah, I was doing a variation on this recently (wondering about the same question). Reversing the latitude of the island of Jersey ("extreme weather is rare due to the island's mild climate") takes you to the Kerguelen Islands ("snow throughout the year as well as rain"). But the contrast there is to do with the Azores High and the Roaring Forties. Local climates are complicated.