Ottawa will be half as warm on Thursday as it was on Tuesday, with frost overnight

A sunny sky in Ottawa on May 20, 2026. (CTV News Ottawa)

Cooler air has moved into the Ottawa region, with Thursday’s forecast high being roughly half of the hottest day of the year.

Ottawa saw a high of 29.2 C on Tuesday. Just two days later, the temperature might only rise to 15 C at most.

The average high for this time of year is around 21 C.

There will be plenty of sunshine on Thursday in the capital.

Overnight, expect a low of 0 C with patchy frost.

A yellow advisory - frost was issued for Ottawa on Thursday, warning of potential damage to trees, plants, and crops overnight as the temperature dips to around the freezing mark early Friday morning.

“Take preventative measures to protect cold-sensitive plants, trees, and crops. Cover up plants, especially those in frost-prone areas,” Environment Canada said.

Friday’s forecast is sunny with a high of 20 C.

Clouds move back over the city on Saturday, bringing a 40 per cent chance of showers with a high of 18 C.

Sunday’s outlook is also cloudy with a chance of showers and a high of 20 C.

Monday could see sunshine again, with a high in the low 20s.

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