Winter Weather - Greater Boise Area Winter Climate

If you don’t like snow — you’re in luck. If you LOVE snow — you’re in luck. The weather in the valley is dry, so there is little snow or rain. For those that look forward to winter play, however, the mountains surrounding Boise offer the snow that they seek!

Temperatures

Winter temperatures are typically 30°-50° in the daytime and below freezing at night. There are cold periods (especially during inversions) that can drop the temperatures into the teens or below but also warm, spring-like days — sometimes into the 60’s.

Inversions

In Treasure Valley winters, there are times when cold air gets trapped against the Boise Mountains. This causes cloud cover, fog and lower temperatures for a few anywhere from one day to two weeks. A quick drive to higher elevations will escape the inversion. From there, you can look down on the sea of clouds and temperatures can be 10° warmer.

Snowfall

The Treasure Valley sees very little snow. What snowfall we do get usually comes at night and early morning and is typically melted by noon. Every six to ten years we get a heavy snow year that can leave an inch or two of snow on the ground for several weeks.

Throughout most of the winter the surrounding mountains are capped in snow. Whether it is the short drive to Bogus Basin ski area or an hour north to Idaho City or Garden Valley, expect to see much more snow at higher elevations and in mountain passes.

Driving Conditions

Because there is so little snowfall, roads are mostly dry all winter long in the valley. In fact, the Ada County Highway District (ACHD) does not own a single dedicated plow truck!

During heavy snow years, you will occasionally see trucks dumping sand onto the roadway to add traction while the snow melts. For nights when the roads are still wet and temperatures are expected to drop, trucks spray the roads with a liquid to prevent freezing (this is rare enough to make the news every time it happens).

Daylight

Near the end of December and beginning of January, the days can get as short as 9 hours between sunrise and sunset. On these days, our Mountain Time Zone pushes those sunrises back to about 8:20 AM and sunsets to 5:30 PM.