Another round of heavy showers and thunderstorms for southern Quebec

The first round of thunderstorms Sunday afternoon produced nearly 25mm of rain in Montreal. More showers and storms are possible over the next 24 hours, with as much as 100mm falling locally. (Valley Weather)

Severe thunderstorm watch for southern Quebec.

Heavy rainfall warning for the Ottawa Valley.

A muggy, warm airmass will be the focus for rounds of showers and thunderstorms on Sunday afternoon, overnight into Monday. As much as 100mm of rain is possible in the most persistent storms.

My vacation time has come to an end after a spectacular week along the Acadian Coast in New Brunswick. What a hidden gem, beautiful, warm salt water beaches, excellent seafood and smiling faces. We will be back. I was blessed with ideal weather, not a drop of rain the entire time until we started home.

July was wet in southern Quebec, with 98.9mm, nearly 4 inches of rain falling at Trudeau Airport. Summer 2026 is quickly turning into the fire versus flood year. We have experienced significant wildfires across Ontario, and they are now sweeping across parts of British Columbia and the Pacific northwest. Smoke is spreading east across the Prairies and into northwest Ontario.

Last week, major flash flooding occurred across portions of the Ohio Valley and Great Lakes, into Ontario and New York. I measured nearly 45mm of rain at my home on Tuesday, July 28, but thankfully, no flooding was reported in our region this time.

Tuesday, July 28 along the Acadian Coast overlooking the warm, salt waters of the Northumberland Strait. If you have not toured the Acadian Coast of New Brunswick, you are in for a treat. What a hidden gem, it was great to spend our vacation in Atlantic Canada, supporting Canadian businesses. (Valley Weather)

As I write, yet another significant, moisture-latent low pressure system is moving from Indiana into southern Ontario and down the St. Lawrence Valley. Showers and thunderstorms have developed in the Montreal region Sunday afternoon, with close to 25mm of rain falling with the first round. More heavy rain is possible this evening and overnight.

Additional showers and thunderstorms are likely on Monday. Total rainfall amounts of 50 to 100mm (2-4 inches) of rain is possible across eastern Ontario and portions of western Quebec. Gusty winds are also possible with the storms, but the main threat will be flooding, especially where storms train or move over the same region.

Conditions should improve on Tuesday, but the weather will remain warm and muggy.

Tornado count up across Canada in 2026

Trees are snapped in half after a tornado near Harrington, Quebec and Tuesday, July 21. The Northern Tornadoes Project continues to investigate the damage and storm track. (Photo Xtreme Chase Quebec)

Investigators with the The Northern Tornadoes Project out of Western University have confirmed that Tuesday's storm near the Laurentian community of Harrington was a tornado. The EF1 storm stripped trees, damaged cars and homes and snapped power poles in half. The storm track was estimated at 10km long and at times up to 1km wide. The tornado was capable of winds up to 175km/h. Many roads in the community were blocked with debris. Thankfully there were no injuries.

If it was a tornado, it would be the 4th in Quebec to date in 2026. Quebec has been lucky. Across Canada, tornadoes are on the increase, with 83 so far this year, compared to the long-term average of 65. Leading the way is Saskatchewan with 34, or 233 percent of normal, followed by Alberta at 27. Ontario with 8 and Quebec's 3 trail far behind. The United States is still has the dubious honour of leading the away when it comes to tornadoes, with 1017 to date in 2026.

Significant damage was reported around Harrington after Tuesday afternoons storms went through. (CBC)

Very hot and at times humid weather pushing north around the heat dome over the midwestern United States along with frequent cold fronts sliding southeast from northern Canada, have been responsible for the active season. There is no end in sight to this pattern. If anything, it may intensify, with hot air expected to surge into the southern Prairies this week as the heat dome expands north once again.

Montreal has managed to avoid wind damage with most of the storms, however there has been significant flash flooding at times, as well as tens of thousands of lighting strikes this summer, that has helped fuel and active fire season in Ontario and Quebec. Whether or not you believe in climate change, our planet seems rather stressed these days.

Thankfully, the weather seems calm for Montreal this weekend. We can expect a near-perfect summer weekend, with sunny skies, light winds and temperatures in the upper 20s (81 to 85F). Overnight lows will be comfortable, ranging from 17C to 19C (63 to 66F). The warm air will persist into next week, becoming more humid at times, with an increase in showers and thunderstorms by Tuesday.

If you are enjoying summer vacation, be safe and have fun.

Seasonable weather week ahead - wildfire smoke remains west of Montreal

The annual Notre-Dame-de-L'Ile Perrot car show took place this past Sunday at Pointe-du-Moulin. The show was well-attended, with spectacular near-perfect summer weather prevailing. This was in stark contrast to the washout on Saturday, with showers and thunderstorms all day in Montreal. Rainfall amounts however were lighter than forecast, with only 5-10mm in the Montreal region.(Valley Weather)

The fire situation across western Quebec and northern Ontario remains critical, with hundreds of fires burning. In Quebec, there are 180 active fires according to SOPFEU. Firefighters are already assisting in Quebec from New Brunswick, Prince Edward Island, Alberta and British Columbia. An additional 18 firefighters will arrive from the Untied States, with 43 from France.

With the wind this week predominately from the north and west, smoke should drift across the central Great Lakes and into the upper Midwest. Smoke from Alaskan wildfires is drifting across northern Canada adding to the poor air quality across the west. Montreal will remain on the eastern edge of the smoke fro now.

The weather will turn cooler with some rain across the fire region as low pressure moves well north of our region across Ontario and Quebec. Here in the southern part of the province, we can expect a seasonable week, with highs in the middle 20s and lows in the teens.

Some shower and thunderstorm activity is possible in Tuesday into Wednesday morning. The threat for severe weather is low this week. Otherwise expect sunshine through Saturday.

The hot and humid weather will remain in place across the central portion of the United States this week giving southwestern Quebec and southern Ontario a break. 

Along the Gulf coast, a weak tropical storm is expected this week. Early Monday morning, tropical depression 2 was located 180 kilometres south of Panama City, Florida, with 55km/h winds. The storm is forecast to become tropical storm Bertha this week, while slowly moving northwest towards the Louisiana coast. The main threat with this storm will be heavy rain and flooding from the Florida panhandle to Texas.

Wet Saturday for Montreal - smoke moves south

Widespread air quality advisories stretch across central and southern Ontario and most of the northern and eastern United States. Dense smoke from wildfires burning across northwest Ontario and northern Minnesota have resulted in some of the poorest air quality in the world over the last few days. Little relief is in site as winds oscillate the smokey air back and forth across the international border. (NYSDOT)

The big story this week is the widespread forest and wildfires burning across parched regions of northwest Ontario into western and central Quebec. Over 180 fires are burning in Ontario, with an additional 19 active fires in Quebec. The total in Quebec for the season is now at 326, of which 72 were caused by lightning and unfortunately 241 by human activity. The Ontario fires are beginning to threaten communities, with evacuations being considered for residents of at least 15 municipalities. Some rain is forecast for the weekend, but also the risk of lightning which may spark additional fires.

The skyline of Toronto on Wednesday, covered in thick smoke from wildfires burning in northern Ontario. The city is fourth on the list of poorest air quality among major cities worldwide on Friday morning.

The Ontario fires have sent plumes of thick smoke southeast across the Great Lakes and into major cities like Toronto, Detroit and Chicago. Air quality has been greatly diminished across Ontario as well as the northern and eastern United States. Residents were being urged to remain indoors Friday, as trips to the emergency room for respiratory issues have spiked, especially in Ontario, Michigan and New York.

Here in Montreal, we have been spared the smoke as most has drifted south and west of the city. We may see some smoke return on Sunday as winds veer to the west and northwest behind a strong cold front.

Our weather will be sunny and seasonable on Friday, a near-perfect summer day, with a high temperatures near 25C (77F). Clouds will increase after midnight as a strong area of low pressure moves down the St. Lawrence Valley. Showers and thunderstorms are forecast most of Saturday, with 20-25mm of rain possible. A cold front late in the day Saturday may produce some vigorous thunderstorms, but the severe weather threat for Montreal is low at this time. Daytime highs will be near 25C (77F), with overnight lows behind the rain dropping to a comfortable 15C (59F)

High pressure should build back in Sunday resulting in a very pleasant, sunny day. The high will be near 24C (76F). Wildfire smoke may return to southern Quebec on both Sunday and Monday.

Forest fire smoke diminishes severe weather in Montreal

Dense smoke from northern Ontario wildfires turns day into night in Thunder Bay on Tuesday afternoon. Thunder Bay was one of the warmest locations in the country on Monday, surpassing 40C (104F). Fires have exploded across that region, sending smoke drifting across southern Ontario and into southwestern Quebec. The smoke has resulted in hazy sunshine and very poor air quality. (Sarah Law/CBC)

Plumes of smoke are drifting across Ontario and southern Quebec on Wednesday from massive forest and wildfires burning across northwest Ontario. At least a dozen new fires have erupted this week, fueled by intense heat, over 40C in some locations, and widespread lighting strikes. To date over 450 fires have been reported in Ontario, with 302 in Quebec. Several are burning out of control in both provinces, resulting in very poor air quality across eastern Canada and the United States.

In fact, early Wednesday morning, Toronto had the poorest air quality of any major city in the world, with a AQI rating of 192, in the unhealthy range. Montreal sits at 73 by comparison, in the moderate range. Air quality advisories are widespread across Ontario. The smoke is obscuring the sun and resulting in a very smokey smell in the air. 

Gusty west winds up to 50km/h are helping to spread the smoke across southwestern Quebec. Conditions will remain poor into Thursday before the arrival of a cold front pushes the smoke south.

The smoke on Tuesday managed to cap the atmosphere here in southern Quebec, resulting in a greatly diminished thunderstorm threat. Capping the atmosphere occurs when warmer air aloft and cooler air at the surface, results in supressing vertical air movement and thus thunderstorm development. Temperatures across our region were around 30C (86F) as opposed to the middle 30s (90s) that were forecast.

Despite the cap, storms still developed, some severe, but the threat was greatly reduced during the daylight hours. Stronger storms did occur after dark, but mainly west of Montreal and south into New York. Those storms produced large hail in parts of the Ottawa Valley as well as the Seaway Valley of upstate New York into the Adirondacks.

The storms did result in over 10,000 lightning strikes over a 24 hour period from Ontario across southern Quebec and into the northeastern US. Earlier in the day Tuesday, a swath of strong storms affected the region between Montréal and Quebec City, southeast across the Eastern Townships prompting a tornado watch by Environment Canada. As I write, no tornadoes were reported.

The weather will remain hazy and warm in Montreal through Thursday.

Elevated risk of severe thunderstorms with the chance of a tornado

Strong and dangerous thunderstorms are possible Tuesday afternoon in the Montreal region, with the risk of isolated tornadoes across southern Quebec. Stay weather alert today and listen for subsequent warnings which will be issued for specific regions as the threat develops. (Valley Weather)

Severe Thunderstorm Watch in effect for metro Montreal

The risk for dangerous weather is elevated today for southern Quebec trhough Tuesday evening. Have a method to receive updated weather warnings and a plan to seek safe shelter immediately if threatening weather approaches.

All the ingredients are present today for a significant severe weather outbreak across eastern Ontario and southwestern Quebec. The parameters are as high as many forecasters and amateurs alike have seen across our region. Hot and humid air is in place, with the trigger being a cold front slipping from north to south across our region late this afternoon. We have strong winds high in the atmosphere and deep tropical moisture available at the surface. 

I still think the greatest threat for a tornado would be east of Montreal, but that does not make these storms any less dangerous for Montreal. Stay alert.

The latest severe weather update from Environment and Climate Change Canada (ECCC), places our region under an elevated risk for severe thunderstorms Tuesday afternoon. The primary threat will be strong winds and hail, but flash flooding and isolated tornadoes are possible as well.

Strong thunderstorms along with isolated supercells are expected to develop late this afternoon north of the city, and move across the Montreal region between 4pm and 6pm, with the severe threat remaining until midnight.

The storms will be capable of powerful straight line winds in excess of 100km/h, large hail, torrential rain, flash flooding and frequent lightning. Some of the storms will be capable of rotation and isolated tornadoes are not out of the question. If a tornado does occur it could be particularly strong with this setup, and travel great distances with the parent storm.

Temperatures will be very warm and muggy, with highs in the middle 30s in Montreal. The one thing I am seeing this morning is the presence of cloud cover and forest fire smoke aloft in the atmosphere. We will see what type of an impact this has on the temperatures and eventual storm development as the day progresses.

The threat for severe weather should end by midnight in Montreal.

Be prepared for severe weather today. Theses storms are capable of wind damage, power outages and challenging driving conditions in torrential rain. The threat will extend from the Ottawa Valley to Quebec City and south into northern new York and New England as well as western New Brunswick to the east.

Surge of heat and humidity for Montreal

A perfect retreat during the warm summer weekend, along the St. Lawrence River in LaSalle overlooking the Lachine Rapids. Just a few fair weather clouds dotted the sky the entire weekend, with comfortable daytime highs near 28C (83F), and lows near 16C (60F), along with low humidity. It was an ideal weekend for anything outdoors in Montreal. (Valley Weather Photo)

Widespread heat and humidity warnings are in effect from North Dakota to eastern Ontario and New England and will likely be issued for parts of Quebec for Tuesday.

Some of the warmest temperatures so far this summer are set to surge into southern Quebec and Ontario this week. How warm? Dozens of record highs were established in Manitoba over the weekend, as highs topped out in the middle 30s. Even overnight temperatures remained in the upper 20s. Humidex reading were as high as 45C. That heat is set to arrive Monday and spread east.

For Montreal, Monday will feature hazy sunshine, with a high close to 30C (86F). A few clouds and perhaps an isolated shower or thunderstorm are possible late in the day, but the risk is low. Warm southwest winds will develop Monday and increase on Tuesday, gusting 20-50km/h at times.

That breeze will usher in very high humidity, along with temperatures as warm as 35C (85F) across some southern Québec locations on Tuesday. Morning lows on Tuesday and Wednesday will be very warm, in the middle to upper 20s for most locations. Some smoke from northern Quebec forest fires is possible, especially in the Ottawa Valley.

On Sunday, parts of northwest Ontario, including Sioux Lookout, flirted with the 100F (37.8C) mark. There is a chance that some locations from Windsor, Ontario east towards western New York may reach 100F Tuesday. I think Montreal will remain below our all-time record high of 37.6C (99.6F) set on August 1, 1975. We should easily challenge the daily record high of 33.3 (91.9F) set in 1921.

Along with the heat will be high humidity levels, pushing humidex values into the middle 40s for most locations. A cold front late Tuesday is expected to produce some very strong if not severe thunderstorms along and south of the St. Lawrence Valley. There is an isolated risk of some supercell storms, that could produce strong winds, hail, heavy rain and even an isolated tornado. The threat would be between 6pm and midnight for southern Quebec.

Warm but less-humid weather will continue for the rest of the week, with seasonably warm highs in the upper 20s.

The fire situation remains serious across central, western and northern Quebec. Any type of outdoor fire remains prohibited across all of Quebec north of the St. Lawrence River, and is highly discouraged in other regions. To date, 295 fires have occurred in Quebec this year, consuming more than 102,000 hectares of forest. Of those fires, 227 were caused by human activity, with 56 blamed on lightning according to SOPFEU.