Ottawa, Canada's capital, sits on the Ottawa River in eastern Ontario at approximately 45.42°N, 75.70°W. It has a humid continental climate (Köppen Dfb) with very cold, snowy winters and warm, humid summers — it is one of the coldest national capitals in the world. Its inland location, well away from any moderating ocean, gives it a large annual temperature range and four strongly defined seasons.

Summer, from June to August, is warm and humid, with July the warmest month — average highs around 26–27°C. Hot, muggy spells fed by air from the United States can push the humidex into uncomfortable territory, and afternoon thunderstorms are common. It is among the sunniest times of year, drawing people onto the rivers, canals and lakes around the city.

Winter is long, cold and snowy. January, the coldest month, averages highs around -6°C and lows near -15°C, with deep cold snaps dropping well below -25°C and bitter wind chill on top. Snow lies on the ground for much of the season — Ottawa sees snow deeper than a centimetre on around 120 days a year — and the frozen Rideau Canal famously becomes the world's largest skating rink. This is a genuinely harsh winter city.

Ottawa receives around 900–950 mm of precipitation a year, spread fairly evenly through the seasons with a summer thunderstorm peak, plus substantial winter snowfall averaging well over two metres. Late winter is the driest time. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Ottawa's continental setting produces one of the widest comfortable-to-brutal seasonal swings of any major city — from humid 30°C-plus summer afternoons to -30°C winter nights. Autumn is a highlight, when the maple forests of the Ottawa Valley turn brilliant shades of red and gold before the long winter sets in, while spring brings the thaw and river flooding from melting snow.

To follow any single measurement in Ottawa more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.