Watch your plants: Canada's frost threat will linger past the May long weekend

Digital WritersThe Weather Network
Published on May. 15, 2025, 7:25 PM

A chilly and below seasonal second half of May could freeze your garden plans

For those who may feel eager to get into the planting season, you'll want to wait a little bit longer. The general advice has always been to hold off until after the May long weekend before it is safe to plant, however, this year that may not ring true.

DON'T MISS: Canada's unofficial kickoff to summer won't feel like it for most

The long range trend is favouring cold air to impact large parts of Canada through the second half of May.

Baron - Temperature pattern next 7 days Canada - May 15

"Colder than normal temperatures will dominate across much of Canada during the weekend, and even beyond into the final week of May," says Rachel Modestino, a meteorologist at The Weather Network. "While temperatures will still be changeable at times, conditions will likely lean cooler than normal from the Great Lakes to Atlantic Canada, and also across B.C. and the Yukon. The Prairies should balance out near normal."

RELATED: A rain barrel can up your gardening game. Here's how

With more cold air available this May, many areas will still have a frost or freeze risk after the May long weekend. This risk is especially true during clear nights where our daytime heat can easily escape.

Baron - Canada temperature anomaly - May 16-21

Those most at risk are for rural regions in the provinces listed above. That includes parts of the Prairies, and much of Ontario, including inland sections of the south. However, it is too early to identify the specific threat areas and times.

Southern urban and suburban areas should be on the safer sides. That includes cities and towns closer to the Great Lakes like Toronto, or further south like Windsor, where there's a lower frost risks than those inland. Similar is true for B.C.’s coast like Vancouver and Victoria.

Content continues below
Baron - Key ingredients frost formation - May 15

DON'T MISS: Summer sneak peek: Canada's warm season goes on cruise control

While we may be eager to get to the summer weather and our plants in the ground, May 2025 might favour those who wait a little bit longer.

WATCH: Protect your plants from frost, look for the '3 Cs' in the forecast

For a better idea of planting in your area, here's a more detailed look at the average last date of spring frost.

British Columbia:

  • Vancouver: March 19

  • Comox: April 1

  • Abbotsford: April 3

  • Victoria: April 4

  • Pitt Meadows: April 11

  • Squamish: April 19

  • Kamloops: April 25

  • Penticton: April 30

  • Quesnel: May 22

  • Smithers: May 26

Alberta:

  • Medicine Hat: May 12

  • Cold Lake: May 19

  • Calgary: May 21

  • Lethbridge: May 21

  • Grande Prairie: May 21

  • Brooks: May 22

  • Red Deer: May 22

  • Edmonton: May 27

Saskatchewan:

  • Saskatoon: May 19

  • Assiniboia: May 20

  • Kindersley: May 21

  • Regina: May 23

  • Prince Albert: May 24

Manitoba:

  • Brandon: May 18

  • Winnipeg: May 23

  • Gimli: May 25

  • Churchill: June 18

Ontario:

  • Windsor: April 17

  • Toronto: April 27

  • Ottawa: April 29

  • Hamilton: May 1

  • London: May 3

  • Sudbury: May 18

Quebec:

  • Montreal: April 29

  • Quebec City: May 10

  • Maniwaki: May 16

  • Val D’or: May 31

  • Gaspe: June 4

Atlantic Canada:

  • Yarmouth: April 28

  • Fredericton: May 14

  • Charlottetown: May 17

  • Moncton: May 19

  • Bathurst: May 20

  • Sydney: May 22

  • Miramichi: May 23

  • St. John’s: May 28

  • Gander: May 31

With files from Rachel Modestino, a meteorologist at The Weather Network