30-50+ mm: Much warmer week in Ontario comes with heavy rain, storm risk
Southern and eastern Ontario will see unseasonably warm temperatures near 20°C this week, accompanied by gusty winds up to 60 km/h and moisture-fuelled storms. Heavy rain, thunderstorms, and showers are expected through midweek
Don’t forget an umbrella while heading out in the coming days, as southern Ontario will experience a warmer pattern, but with multiple systems bringing increased chances of heavy rainfall and thunderstorms.
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Some areas could see as much as 50-100 mm of rain through the week ahead. Special weather statements and yellow-coded rainfall warnings are in effect.
Weather Highlights:
Southern and eastern Ontario will experience daytime highs in the high teens to above 20°C this week
Widespread showers Monday precede thunderstorms moving into Ontario overnight, bringing heavy downpours, lightning, and small hail Tuesday morning. Wednesday and Thursday continue the stormy trend
Water will likely pool on roads and in low-lying areas. Don't drive through flooded roadways
Major warm-up marked with period of heavy rain and thunderstorms across southern Ontario
A surge of warm southerly air is set to dominate southern and eastern Ontario this week, with daytime highs reaching the high teens to above 20°C—temperatures more typical of late May than mid-April. Strong southwesterly winds, gusting up to 60 km/h, will accompany this warmth, alongside moisture-rich systems drawing energy from the Gulf of Mexico. Colder air fighting back in the north will create an active storm track over southern Ontario this week.
Monday: Persistent showers are expected throughout the day. A strong cluster of thunderstorms from the U.S. is set to cross Michigan overnight, potentially impacting the Lake Huron shores by early Tuesday morning.
Tuesday: Early-morning thunderstorms will track through southwestern Ontario and the Greater Toronto Area (GTA), potentially disrupting the morning commute.
These storms may bring heavy downpours, frequent lightning, and small hail.
Rainfall totals could reach 30-50 mm in areas such as Goderich, London, and Sarnia, with 20-30 mm expected for the GTA and Niagara.
Afternoon conditions remain mild, with a risk of a passing storm and isolated severe thunderstorms in southwestern Ontario by evening.
Wednesday: A similar weather pattern unfolds, with overnight storms originating in Michigan progressing into southern Ontario.
Conditions remain uncertain for the afternoon as a warm front may lift thunderstorm ingredients northward. Areas such as Windsor, Lake Erie, and London could see storm development depending on the timing of the front.
Thursday: Warm, elevated showers and thunderstorms persist as the warm front shifts northward.
Daytime highs soar above seasonal norms
Temperatures will consistently remain 10°C above seasonal norms, with Toronto's Pearson International Airport forecast to record 5-6 consecutive days near 20°C this week.
Typically, Toronto’s Pearson Airport averages fewer than three days above 20°C in April. However, mid-April 2023 saw more intense warmth, with temperatures climbing to 29.4°C on April 12, 2023, setting a notable benchmark for this time of year.
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Stay tuned to The Weather Network for the latest forecast updates across southern Ontario.