Winters in the Boise area are moderately cold and dry. The mountains and foothills that surround Boise and the Treasure Valley do get a good share of snow typically in late November-March, however, Boise typically experiences mild snowfall, under the national average at 18" annually...that's just enough to enjoy the sparkling white ground and watch it quickly melt. The entire Valley does benefit from sunshine all year long with higher than other US Cities average days of sunshine annually.
SPRING IN BOISE
Spring is a beautiful time of year in the Boise area with blossoming trees and flowers popping up bright colors throughout the Valley, however it also brings a range of temperatures ranging from the 50s to the 80s and can change rapidly during mid-March through mid-May. Precipitation is higher this time of year with an average of 1.30" of rainfall between March-May before the warmer temperatures and dryer season begin.
SUMMER IN BOISE
The ave temps between the 3 hottest months (July-Sept) average at over 82° with the warmest part of the day peaking at around 6 PM. Triple digit days do exist and can last for up 2-3 weeks. Evenings and nights tend to cool down and have clear skies. Wildfires are a risk in Idaho however, Boise tends to struggle more with the smoke from these fires than the fires themselves. Count on several days of smoke during these months. There's also a lot of light in Summer...it can stay light out til after 10PM in mid-Summer.
FALL IN BOISE
By mid-September the cooler temperatures arrive in the Valley with an average high ranging from low 60s to mid-70s. The first hard frost usually arrives mid to late November in the area. Fall colors and leaves falling make it one of the most beautiful times of year due to Boise being the "City of Trees". September is one of the mildest months for temperatures and brings in lots of visitors. Plan on pulling out the jackets in October and the scarves by November.