Lethbridge has a semi-arid climate (Köppen climate classification BSk) with an average maximum temperature of 12.3 °C (54.1 °F) and an average minimum temperature of −1.1 °C (30.0 °F). With precipitation averaging 365 mm (14.4 in)–386.3 mm (15.2 in), and 264 dry days on average, Lethbridge is the eleventh driest city in Canada. Mean relative humidity hovers between 69–78% in the morning throughout the year, but afternoon mean relative humidity is more uneven, ranging from 34% in August to 64% in January. On average, Lethbridge has 116 days with wind speed of 40 km/h (24.9 mph) or higher, ranking it as the second city in Canada for such weather.
Its high elevation of 929 m (3,047.9 ft) and close proximity to the Rocky Mountains provides Lethbridge with cooler summers than other locations in the Canadian Prairies. These factors protect the city from strong northwest and southwest winds and contribute to frequent Chinook winds during the winter. Lethbridge winters have the highest temperatures in the prairies, reducing the severity and duration of winter cold periods and resulting in fewer days with snow cover
