Why the East Coast is warmer than the West Coast in the middle of December

Temp December 16NOAAWeather for December 16, showing a warmer-than-average East Coast.

No, this one isn’t directly because of global warming.

You can pin this month’s weird weather flip on the record-breaking El Niño weather pattern that’s happening this year.

It’s pushed the jet stream, which usually keeps the East Coast cool, up north. That’s what’s giving the East Coast spring-like temperatures.

At the same time, a storm that blew through the West Coast over the weekend brought chilly weather to the West Coast. That’s why the weather in Los Angeles (at noon Eastern Time, it was 48 degrees Fahrenheit there) is a few degrees colder than New York (which was 54 degrees Fahrenheit at the same time).

So if you’re dreaming of a White Christmas and you live out east, don’t hold your breath. This warmth will likely stick around the East Coast through the holidays. 

We’re currently in one of the strongest El Niño years on record. El Niño, a weather pattern that’s characterised by warmer-than average water temperatures in the Pacific Ocean, can often lead to drought, flooding, and otherwise unexpected weather events around the world. It has an effect on the jet streams, or the strong winds that are responsible for moving weather systems around the world. It’s what usually makes the East Coast chilly in the winter.

But because the temperatures in the Pacific are all mixed up, it’s throwing the jet stream off, leading it to push cold air far north, missing the East Coast almost entirely. 

Elsewhere in the US, the West Coast is getting hit by huge storms coming from the goofy jet stream coming off the El Niño-level warmth in the Pacific. That’s what made a city in Arizona the coldest spot in the continental US over the weekend. 

Over in the northern Midwest, mainly Minnesota and the Dakotas, snowy weather is coming. But for traditionally freezing states, such as Illinois and Wisconsin, the weather’s hanging out in the high 40s through next week. 

Moral of the story: Head west if you’re really craving a chilly Christmas. 

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