Boise is situated in a wide river valley at the foot of the Rocky Mountains. The Boise River runs out of a canyon to the south and through the center of the city, joining the Snake River about 40 miles to the north. The climate is tempered year-round by air from the Pacific Ocean. Summers are dry with hot periods that rarely last more than a few days; autumn weather is usually ideal. Winter storms produce much of the yearly precipitation; cold spells are common, but warm Chinook winds (moist air from the Pacific) bring periods of mild weather. Low humidity is raised slightly by agricultural irrigation.
| 63.8 square miles (2000) | |
| 2,842 feet above sea level | |
| January, 29.9° F; August, 72.2° F; annual average (mean): 50.9° F | |
| 12.11 inches of rain, 20.9 inches of snow |
