Weather in Calgary

Rain is wet season runs from May to June, inside an annual total of 546 mm. The wettest month is June at 115 mm; the driest is January at 17 mm.

Calgary is in Canada at 51.1°N. The 2001–2020 NASA POWER daily record describes a continental climate with a wide temperature swing. July is the warmest month (average 16.5°C, high 23.4°C) and December is the coolest (average -7.4°C, low -11.6°C). On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are June, July, and August.

Best months to visit Calgary

The three months with the highest comfort score are June, July, and August: June (12.4°C average, 115 mm, 67% humidity); July (16.5°C average, 58 mm, 62% humidity); August (15.7°C average, 61 mm, 63% humidity). They fall in calendar order. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the wet season itself — fewer crowds, greener landscape, heavier rain — aim at May–June instead of the score.

How warm Calgary gets

Monthly average highs run from -3.3°C in December to 23.4°C in July. Nights follow the same curve: -11.6°C in December and 9.7°C in July.

Mean high across all twelve months is 9.5°C and mean low is -1.8°C. These are 20-year grid averages, so a city station can read a few degrees warmer or cooler.

Rain through the year

The wet season in Calgary starts in May and ends in June (May and June). June is the core of it at 115 mm. January is the other extreme, with 17 mm.

A rainy day here is a day with at least 1 mm in the NASA POWER series. June averages 17 such days; January averages 5.

What stands out month by month

January is the driest month, averaging only 17 mm across 5 rainy days. Highs sit near -2.5°C. February brings 20 mm and 6 rainy days; temperatures run from -11.5°C to -1.2°C. March stands apart from the months beside it: 3.5°C / -7.6°C and 26 mm. April: 8.8°C high, -3.1°C low, 46 mm rain, 66% humidity. May is when the wet season typically starts in Calgary: highs near 14.9°C, and rainfall jumps to 74 mm (12 rainy days). By June the wet season is ending. Calgary still sees about 115 mm, but the next month is usually leaner.

Peak heat arrives in July: 23.4°C by day, 9.7°C at night, and 62% humidity. August: 22.6°C high, 8.8°C low, 61 mm rain, 63% humidity. In September, Calgary averages 17.4°C by day and 4.4°C at night, with 53 mm of rain. In October, Calgary averages 9.8°C by day and -1.4°C at night, with 32 mm of rain. November: 2.0°C high, -6.5°C low, 23 mm rain, 77% humidity. The year bottoms out in December. Plan for -11.6°C at night and -3.3°C in the afternoon.

How Calgary compares inside Canada

Toronto is about 2708 km away: Calgary is 5.1°C cooler than Toronto in its hottest month and 228 mm drier over the year than Toronto. Toronto’s wettest month is July (75 mm) versus June here.

Montréal is about 3019 km away: Calgary is 4.9°C cooler than Montréal in its hottest month and 540 mm drier over the year than Montréal. Montréal’s wettest month is October (114 mm) versus June here.