Chicago

When to expect the first freeze, snowfall

Raise a pumpkin spice latte to fall’s return — the autumnal equinox occurred on Sept. 22.

Each day after, we lose a bit bit extra daylight till the winter solstice on Dec. 21, the shortest day and longest night time of the year. The identical phenomenon will happen once more subsequent year to mark the spring, or vernal, equinox on March 20, 2023.

Meteorologists, nonetheless, mentioned goodbye to summer season on Sept. 1, since they like to monitor climate in 4, three-month increments instead of astronomical seasons, that are outlined by equinoxes and solstices.

It’s the good time to observe Chicagohenge.

The rising and setting solar strains up completely with the metropolis’s east-west avenue grid, creating spectacular picture alternatives as the solar is framed inside Chicago’s skyline.

The earliest first freeze on document occurred Sept. 22, 1995, at O’Hare International Airport, the metropolis’s official recording web site. The newest was Nov. 24, 1931.

In 2021, the first freeze didn’t arrive till Nov. 2.

“The first freeze, which is when the temperature drops at or below 32 degrees, typically occurs between Oct. 11 and Oct. 12 across the Chicago suburbs and Oct. 21 to Oct. 30 in the city and along the lakeshore,” Brett Borchardt, meteorologist for the National Weather Service’s Chicago office, instructed the Tribune.

Chicago experiences larger temperatures longer than outlying suburbs due to the heat-island effect. Its location subsequent to Lake Michigan’s heat waters explains why the metropolis and close by suburbs freeze later in the year than their farther-out counterparts.

Frost can develop on clear nights when the air temperature is in the mid-30s, however could be scattered. That’s why, WGN-TV chief meteorologist Tom Skilling says, the climate service “does not keep statistics regarding frost but instead uses the season’s first temperature of 32 (degrees) or lower to define the end of the growing season.”

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“The first trace or more of snow typically occurs on Oct. 30, but has occurred as early as Sept. 25 (1942) and as late as Dec. 5 (1999),” Borchardt mentioned. “The first measurable snow (0.1 inch or more) typically occurs around Nov. 17.”

[ Here’s when Chicago received its first snow of the fall season, going back 135 years ]

Last year, Chicago acquired its first measurable snowfall of the season on Dec. 28 — the newest date of a first snowfall in Chicago historical past going again to 1885.

La Niña is sticking round. The local weather sample that has a cooling impact on ocean floor temperatures is predicted to stay in impact via the finish of the year, in accordance to the World Meteorological Organization. This is the third consecutive year — or a uncommon “triple dip” — of the climate phenomenon.

“It’s unusual for a La Niña to hang on through summer, and even more unusual to go into a third consecutive La Niña — which we would if it hung on into fall,” mentioned Trent Ford, Illinois state climatologist.

Locally, the National Weather Service’s Climate Prediction Center is forecasting temperatures leaning above regular and “equal chances” of above or beneath precipitation from October via December.

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