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Taste of spring in Ontario will also come with rain, flood risk

Monday, March 8th 2021, 10:33 pm - April-like weather spreads into Ontario this week, but that doesn't signal the official end to winter.

A ridge of high pressure is helping to bring a sneak peek of spring to the southern Ontario this week, with a southerly flow allowing for progressively milder temperatures through Thursday. There is a chance the next three days could be the warmest three-day stretch the province has seen in several months.

Enjoy it while you can because winter isn't over, yet, and cooler, but near seasonal temperatures will return for the weekend. There will also some unsettled weather ahead of the temperature drop, with a low-pressure system expected to bring rain late Wednesday night into Thursday.

Visit our Complete Guide to Spring 2021 for an in-depth look at the Spring Forecast, tips to plan for it and much more!

The forthcoming rain and rising temperatures also brings the risk of flooding from snow melting for the Grand River. A flood watch is in effect.


While the warmth hit the southwest first Monday, double-digit temperatures will continue Tuesday and will become much more widespread by Wednesday afternoon, even reaching parts of cottage country and eastern sections. Daytime highs will be into the mid-teens across a good portion of the south, values that are more common for mid-April.


"Tuesday and Wednesday will feel more like early April," says Weather Network meteorologist Dr. Doug Gillham, adding there's also the chance for some overachieve potential. "If we hold onto the sunshine and we can avoid having the wind blow off of Lake Ontario, we will see temperatures climbing into the low to mid teens."

The next threat for rain will arrive late Wednesday night and into Thursday, with gusty winds, though temperatures will remain very mild and through the day on Thursday, as well.

ONTempThurs (Monday PM)


The Grand River Conservation Authority (GRCA) issued a flood watch for the entire river watershed due to the anticipated runoff and potential for ice movement. Conditions will continue to be monitored closely and updates will be issued as necessary.

Warm temperatures, combined with between 10-15 mm of rainfall across the Grand River watershed this week, will result in significant snowmelt and increased runoff into local waterways.

Ice on local waterways is extremely unstable and will break up and shift during this event, increasing the risk of flooding in areas prone to ice jams.

"Flows in local waterways throughout the Grand River watershed are expected to begin increasing on Wednesday and remain elevated into early next week. Runoff from this event will result in flooding in low lying areas typically prone to spring flooding," the group said in the statement.


The short flirt with spring will feel glorious while it lasts, but temperatures will begin to tumble as early as Friday, accompanied by a potential wintry mix.

"Fair weather and cooler (near seasonal) temperatures will gradually press back into the region for the weekend," Gillham says.

ONRain (Monday PM)

By the weekend, temperatures will be back near seasonal for mid-March, making for some changeable weather as the official start to the spring season draws closer.

MARCH OUTLOOK: Expect this month to be 'truly Canadian'

Beyond the weekend, there is the potential for a messy system early next week with rain, ice, and snow for the region. However, it's too early to have confidence in storm track and where we will see the transitions in precipitation type.


Despite the flip-flopping temperatures however, the season overall still looks to tip to the milder side, with no real threat for extended periods of colder weather that has taken over the season during the past few years. Still, a few parting shots from winter should always be expected during March and April, and sometimes even May, before winter finally surrenders.

Be sure to check back for the weather across Ontario as we march into spring.

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