Tuesday was Ottawa’s hottest autumn day on record

Oct. 3, 2023, was Ottawa’s hottest autumn day in more than 150 years of Environment Canada records.

With Wednesday’s forecast, it could have a short reign at the top.

Environment Canada said the temperature reached 30.9 C at Ottawa’s international airport on Tuesday.

The hottest October temperature in records going back to 1872 for Ottawa was 29.4 C, reached twice in the 1890s. The hottest autumn temperature on record was 30.7 C in late September 2017.

The average high temperature in Ottawa for Oct. 4 is 15 C and the average low is about 5 C, according to Environment Canada. Tuesday’s low was 15 C.

Petawawa’s 30.6 C on Tuesday was also a monthly record there, according to Environment Canada.

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Ottawa’s forecasted high for Wednesday is 30 C, above the Oct. 4 record of 27.7 C from 2005 and close to setting an autumn record again.

Daily heat records are also in play Wednesday for many communities around Ottawa such as Belleville, Gatineau, Kingston, Napanee and Trenton, according to data compiled by CBC’s climate dashboard.

Human activity is causing climate change that makes extreme heat more likely, placing vulnerable people, businesses, infrastructure and agriculture at further risk.

The unseasonable heat shouldn’t trigger a proper heat warning from Environment Canada, which issues them when at least two days in a row above 30 C and nights above 20 C are forecast, or when humidity is expected to make it feel like 40 two days in a row.

Humidity is expected to make it feel like 35 Wednesday in the capital.

The forecast calls for Ottawa to reach 26 C Thursday and then fall back to more seasonal temperatures through a wetter Thanksgiving weekend.

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