Yellowknife has a subarctic climate and averages less than 300 mm (12 in) of precipitation annually, as the city lies in the rain shadow of mountain ranges to the west. Thanks to its location on Great Slave Lake, Yellowknife has a frost-free growing season that averages slightly over 100 days. Most of the limited precipitation falls between June and October, with April being the driest month of the year and August being the wettest. Snow that falls in winter accumulates on the ground until the spring thaw.
Yellowknife is on the Canadian Shield, which was scoured down to rock during the last ice age. The surrounding landscape is very rocky and slightly rolling, with many small lakes in addition to the larger Great Slave Lake. Trees such as pine and birch are abundant in the area, as are smaller bushes, but there are also many areas of relatively bare rock with lichen. Yellowknife's high latitude causes a large variation between day and night. Daylight hours range from five hours of daylight in December to twenty hours in June. Twilight lasts all night from late May to early July
