With Boise’s first frost of the season expected this week, the Gem State can expect winter temperatures to shift through the end of the year.

The National Oceanic and Atmospheric Administration released its winter outlook on Thursday, Oct. 17, showing that Idaho can expect minor changes in normal winter temperatures as La Niña is expected to impact winter conditions across most of the country.

Here’s what to expect.

How’s La Niña effect the weather?

A La Niña is when sea temperatures are cooler in the eastern Pacific Ocean, leading to less evaporation, weaker storms and less moisture in the atmosphere, according to NOAA. The colder waters of the Pacific Ocean move toward the surface, pushing the jet stream further north toward Alaska before sinking southward into the northern United States.

“La Nina conditions are expected to develop later this fall and generally lead to a more northerly storm track during the winter months,” according to NOAA’s 2024-2025 Winter Outlook.

While the southern United States is expected to have a drier and warmer winter, northern states like Idaho can expect temperatures slightly below normal and slightly more precipitation.

What are the consequences for Boise?

Northern and central areas of Idaho can expect slightly colder weather and more precipitation between November and January, according to Les Colin, a senior forecaster with the National Weather Service in Boise.

However, in Boise and the rest of southern Idaho, precipitation is expected to be normal for this time of year and residents can look forward to slightly warmer temperatures.

“What this suggests is that we would have more snow than normal, because normal temperatures would certainly bring a lot of snow to the mountains, and the additional precipitation would bring more than normal amounts of snow,” Colin said in a telephone interview with the Statesman. “So what it shows here is normal or slightly above normal temperatures in southern Idaho, but above normal precipitation would equate to above normal snowfall, especially in the mountains.”

Colin said he also expects excess snow in the mountains and northern Idaho as temperatures will be colder and below freezing. There is also a chance, he said, that this weather pattern will continue into March next year.