2019 ties for second-coldest October in Salt Lake City history

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SALT LAKE CITY — A day after the lowest temperature in Salt Lake City during October was recorded, there is another spot in history for ‘Octoburrr.’

With an average temperature of 46.5 degrees Fahrenheit, 2019 tied 1883 for the second-coldest October in the 145 years the National Weather Service has tracked the city's weather, the weather service reported Thursday. The coldest October on record was in 1919, which had an average temperature of 44. 5 degrees.

That announcement followed a slew of new low-temperature records set across the state throughout the month.

With today's high temperature of 43°F at SLC, the average temperature for the month will be a bone chilling 46.5°F, tied for the second coldest October on record with 1883. The coldest ever average temperature for October was 44.5°F, set in 1919. #utwx
— NWS Salt Lake City (@NWSSaltLakeCity) October 31, 2019

So, why was October so cold?

Brian McInerney, a hydrologist with the weather service, said that it had to do with an abnormality in a high-pressure pattern that typically sets up like a "spinning wheel" over the western U.S. during this time of the year.

Air coming off the Pacific Ocean normally hits high-pressure patterns and moves into Canada before dropping back down past Utah into Colorado. However, that pattern didn't set up the same way for chunks of October 2019.

"Take that wheel and kind of squish it so it's really long and narrow. Now you have all the energy coming off the Pacific, it hits, that high pressure gets shunted north, but now — since it's a lot more narrow and not as round — it goes all the way into the Northern Yukon area up into the Arctic Circle, goes around the high pressure, and then drops straight south down through British Columbia, through Alberta, and then straight down to our area," McInerney said.

The end result was a series of record-breaking, cold-temperature events that led to the coldest October in a century. According to the weather service, 1946 (46.6 degrees) and 1970 (47 degrees) round out the five coldest Octobers recorded since 1874.

McIrnery said differences in warming temperatures in the Arctic and warming temperatures at the equator have led to changes in normal jet streams, which leads to oddities in weather and records. This cold October, however, is vastly different than recent October abnormalities in Salt Lake City. For example, the warmest October on record (60.5 degrees) was set just four years ago, and the fourth-warmest was set in 2016, according to weather service records.

If changes in jet stream patterns continue, McInerney said an increase in bizarre weather will likely happen in the future.

"You'll see kind of weird, anomalous weather patterns like we're seeing right now, where things you'd used to see in the past are a little different," he said, noting that temperatures and weather patterns will eventually revert back into the normal for autumn. "Every once in a while, we'll see these (patterns)."

Halloween forecast

The final few hours of the month are when trick-or-treaters are out and about for Halloween. It will remain chilly Thursday night. Across the Wasatch Front, it will be in the low 40s in the late afternoon before dipping to mid-30s by 8 p.m., and into the upper-20s before midnight.

In Logan, temperatures are expected to remain in the mid-30s in the late afternoon before dipping into the upper-20s by 8 p.m., and then dropping into the teens overnight.

In St. George, temperatures are expected to hover around 50 degrees by 8 p.m. and drop into the lower-40s and upper-30s overnight.

Forecasts for the rest of the state can be found on the KSL Weather page.