Edmonton has a relatively dry humid continental climate (Koppen climate classification Dfb, USDA Plant Hardiness Zone 3a) with extreme seasonal temperatures-although the city has milder winters than either Regina or Winnipeg, both located at a latitude farther south. It has warm summers and cold winters, with the average daily temperatures ranging from ?11.7 °C (10.9 °F) in January to 17.5 °C (63.5 °F) in July. Annually, temperatures exceed 30 °C (86 °F) on an average of four to five days (but can occur often, anytime from late April to mid September) and fall below ?20 °C (?4 °F) on an average of 28 days. The highest temperature recorded in Edmonton was 38.3 °C (100.9 °F), on August 5, 1998. Some areas, however, such as the City of St. Albert and Sherwood Park, recorded temperatures of 37.7 °C (99.9 °F) on July 22, 2006. The coldest temperature ever recorded at city centre was ?40.6 °C (?41.1 °F) on January 26, 1972 - this was the only time since recordings began in 1953 that city centre has recorded a temperature below ?40 °C (?40 °F). The coldest overall temperature recorded in Edmonton was ?49.4 °C (?56.9 °F), on January 19 and 21, 1886. The year 2006 was a particularly warm one for Edmonton, as temperatures reached 29 °C (84 °F) or higher more than twenty times during the year, from as early as Mid-May and again in early September. Typically, summer lasts from late June until late August, and the humidity is seldom uncomfortably high. Winter lasts from November to March, and varies greatly in length and severity. Spring and autumn are both short and highly variable. Edmonton's growing season is from May 7 to September 23; Edmonton averages 140 frost free days a year. At the summer solstice, Edmonton receives seventeen hours and six minutes of daylight, with twilight extending throughout the entire night during summer. Edmonton receives 2,299 hours of sunshine per year and is one of Canada's sunniest cities.

Edmonton has a fairly dry climate. On average, Edmonton receives 476.9 millimetres (18.78 in) of precipitation, of which 365.7 millimetres (14.40 in) is rain and 111.2 millimetres (4.38 in) is the melt from 123.5 centimetres (48.6 in) of snowfall per annum. Precipitation is heaviest in the late spring, summer, and early autumn. The wettest month is July, while the driest months are February, March, October, and November. In July, the mean precipitation is 91.7 mm (3.61 in). Extremes do occur, such as the 114 mm (4.49 in) of rainfall that fell on July 31, 1953. Summer thunderstorms can be frequent and occasionally severe enough to produce large hail, damaging winds, funnel clouds, and even tornadoes. However, tornadoes near Edmonton are far weaker and short-lived compared to their counterparts farther south. Tornadoes as powerful as the F4 tornado that struck Edmonton on July 31, 1987, killing 27, are rare.
A massive cluster of thunderstorms occurred on July 11, 2004, with large hail and over 100 mm (3.94 in) of rain reported within the space of an hour in many places. This "1-in-200 year event" flooded major intersections and underpasses and damaged both residential and commercial properties. The storm caused extensive damage to West Edmonton Mall; a small glass section of the roof collapsed under the weight of the rainwater, causing water to drain onto the mall's indoor ice rink. As a result, the mall was forced to undergo an evacuation as a precautionary measure