No
Why? Because you should be inside at home! #StayHome
But if you absolutely had to go out to get groceries, medication or other essential travel, No, you don't need a jacket.
Based on the weather in Markham, ON, Canada as of May 25, 2020 9:54am local time.
Now
Partly Cloudy
Temp: 72°F22°C
Wind: 5 MPH8 KPH
Precipitation: None
Temp: 72°F22°C
Wind: 5 MPH8 KPH
Precipitation: None
Today
Next 2 hours: No
Next 4 hours: No
Next 8 hours: No
Tomorrow
No
Partly cloudy throughout the day.Low of 64°F18°C, High of 84°F29°C
Wind: 5 MPH9 KPH
Precipitation: 12% rain