Hailey is a city in and the county seat of Blaine County, in the Wood River Valley of the central part of the U.S. state of Idaho. The population was 7,960 at the 2010 census, up from 6,200 in 2000. Hailey is the site of Friedman Memorial Airport (SUN), the airport for the resort area of Sun Valley/Ketchum, 12 miles (19 km) north. The town of Bellevue is a few miles south. From 1882 to 1895, Hailey was the county seat of now-defunct Alturas County.
The city is named after John Hailey, a two-time Congressional delegate from the Idaho Territory.
Hailey is located at 43°30′54″N 114°18′23″W (43.514937, -114.306251), at an elevation of 5,318 feet (1,621 m) above sea level.
According to the United States Census Bureau, the city has a total area of 3.65 square miles (9.45 km2), all of it land.
Hailey has a continental Mediterranean climate (Köppen Dsb). Winters are cold and snowy: there are an average of forty-four days each year which fail to top 32 °F or 0 °C, whilst 199 nights fall below freezing and nineteen nights between November and March will fall to or below 0 °F or −17.8 °C. Spring warms up slowly, with snow falling as late as May. Summer is hot during the day, but cools off into the 40s or 50s at night.