The summer finally departs as winter weather moves into Colorado this weekend.

A slow-moving storm system heading in from Utah has brought snow to the high mountain passes in the southwestern part of the state, which will continue this weekend. The system — though unlikely to bring any wintery precipitation to the metro Denver area — will still produce autumn-like temperatures for the first time this season.

A winter storm warning was in effect from 6 a.m. Friday to noon Sunday for the San Juan Mountains. Heavy snow is possible with total snow accumulations of 10 to 20 inches possible above 8,500 feet. Winds could gust as high as 45 mph, according to the National Weather Service.

Additionally, eastern portions of the San Juan Mountains, as well as portions of the Sangre de Cristos, are under Winter Weather Advisories for up to a foot of new snowfall.

The National Oceanic and Atmospheric Administration (NOAA) has a significant portion of the area listed as potential “major impacts,” meaning drivers should avoid the area and that the area could experience “considerable disruptions to daily life” until Monday morning.

“Unfortunately, it’s kind of warmer to start out. We haven’t got the cold air yet,” Dennis Phillips, a meteorologist for the National Weather Service Grand Junction, said of the snow in the San Juan Mountains around 2 p.m. Friday.

Higher areas like Coal Bank Pass, Molas Pass and even Silverton have begun experiencing snow, according to Phillips.

The accumulation in the area has been limited due to the warmer temperatures, but is likely to change when the cold front slides over from Utah on Friday evening, Phillips said.

Phillips said he expects a “decent” amount of snow down in the San Juans over the weekend, bringing in the first major fall snowstorm the state has seen this season.

“We obviously had a very warm and anomalously dry period before this,” Phillips said. “We got some snow in September, but it got melted back. This was just the first big storm to come along and bring down that pattern. Now, we’re snowing again.”

Things in the metro Denver area and along the Front Range look less frigid going into the weekend, though.

The system is forecast to bring rain showers to the Denver area with high temperatures in the low 60s on Friday and low 50s on Saturday in Denver. The high temperature on Saturday may not break 50 degrees.

Rain showers will gradually spread across the Front Range on Friday afternoon, with the bulk of the widespread rain showers likely beginning Friday evening or Friday night and lasting into the day on Saturday.

Expect a cold and dreary day on Saturday with lows in the middle 30’s. The first freeze is not in the forecast for Denver, but it may come very close. Snow accumulation also remains very unlikely in Denver.

Temperatures start to rebound, Sunday, with Denver highs returning to the lower 60s. Precipitation will start to move out, clearing out of Colorado by the overnight hours.

By the beginning of next week, temperatures are set to return to the 70s, continuing the strangely dry and warm season.

“It’s been quite warm, especially to start the month of October,” Zach Hiris, a meteorologist with the National Weather Service Boulder, said, noting that things are still sitting a few degrees above the average temperature for the month.

While Hiris also referred to this year’s weather as anomalous, he said it may now be a thing of the past after this storm, with the cold weather potentially breaking the 80-degree weather the state has seen.

The winter season may end up being normal, despite the unusual start. But both Hiris and Phillips said it’s up in the air and impossible to tell.

Both added that the warm and dry start to the fall does not mean that the winter will stretch well past its normal range. It’s a late start, not a moved window, they said.

“In the northeastern half of Colorado, we’re looking at equal chances of seeing above or below normal temperatures and precipitation,” Hiris said. “The long-term signals look pretty average for this winter.”

The latest first measurable snowfall in Denver was Dec. 10, 2021, and before that, in 1934, when the first snow occurred on Nov. 21. The earliest was Sept. 3, 1961. The average first snow date is right around the middle of October, Hiris said.

A La Niña pattern is expected to hit the country, according to a recent forecast by NOAA. The weather pattern would mean trade winds would be stronger than usual, pushing warm water toward Asia, while colder water comes to the Pacific coast of the country.

Because Colorado is off the cusp of the polar jet stream, a La Niña can affect snowfall in the state, often leading to less snow in the southern half and more in the northern.

According to NOAA, the La Niña has a 60% chance of setting in by the end of November and could last until March 2025.

The La Niña is going to be fairly weak though, according to Phillips, so it’s nearly impossible to predict what it could mean for both the northern and southern part of the state.

“It’s very misleading to say we’re in a La Nina winter so this means this for these mountains. It depends on how it all shakes out,” Phillips said.

The Denver Gazette’s news partners 9NEWS contributed to this report.