Autumn has arrived in the northwest of the country. The leaves are changing, jack-o-lanterns are out, it’s getting cold.

After Tuesday night, the sun will not set again until 6 p.m. until March 9th.

Tuesday could be the last day of the season with temperatures above 70 degrees, said Greg Koch, a meteorologist with the National Weather Service in Spokane.

Temperatures are expected to fall this week, with a breeze and showers on Wednesday. Highs will be in the 50s Thursday and Friday.

Overnight lows could fall below freezing to the mid-20s early Friday morning, Koch said.

The weather should weaken a bit over the weekend and temperatures should drop back below 60°C.

Snow is forecast for the Cascades above 4,000 feet Wednesday night through Thursday morning. Winter driving conditions could impact Stevens and Washington passes, where more than 2 inches of snow is forecast.

“Some of the snow may not last long this early in the season,” Koch said. “But some of the higher ground could extend a few inches around the passes.”

The cold of autumn heralds a winter that is colder and wetter than average. Koch said there is a 75% chance of a weak La Niña.

La Niña is a climate pattern opposite to El Niño, characterized by cooler currents around the equator in the Pacific Ocean.

In general, Koch said, La Niña winters bring more precipitation to the Northwest, particularly in the mountains, and cooler temperatures, with occasional blasts of arctic air that can push temperatures well below normal.

The last La Niña cycle lasted three winters from 2020 to 2023. Last winter was a moderate to strong El Niño with a relatively warm and dry season, Koch said.

Additional moisture would be good news for last year’s drought. A light blanket of snow prompted the Washington State Department of Ecology to declare a drought emergency for most of the state this spring.

More snow would also be welcome for winter recreation after rainstorms early last December melted the snowpack at the region’s ski areas in a rocky start to the season.

When winter approaches, Koch says it’s a good time to prepare vehicles for winter driving and check the tire tread. Those driving through higher elevations should consider bringing a pair of boots, a phone charger and a blanket in the vehicle.