Stormy weather week for southern Quebec

The first frost of the season occurred on Saturday morning here on Ile Perrot. It was very light, with temperatures dropping to 1C (33F). A much colder airmass arrives by next weekend, with widespread frost, freezing temperatures and even some snow possible. (Valley Weather)

Heavy Rainfall Warning for Montreal for Tuesday.

October can be an interesting weather month, like April, with the seasons in full battle mode. Over the weekend, we had a major hurricane in the Pacific Ocean off the coast of Mexico, as well as one impacting the Gulf Coast. The first snow of the season fell across portions of southern Alberta and Saskatchewan, and the remains of hurricane Rachel brought pounding surf and significant flash flood from California into Nevada.

In Montreal, Saturday was as nice a fall day as you can have, with widespread sunshine, light winds and seasonable highs in the teens. The good weather for Montreal has come to an end as clouds and showers are moving in along a weak cold front late Monday. 

That front will stall to our south over northern New England, and may even slowly move north as a warm front Tuesday afternoon. Low pressure will move along the front, tapping into moisture from the remains of Pacific hurricane Rachel. Steady rain and thunderstorms are expected Tuesday, with as much as 40-60mm from Montreal south to the United States border and eastward into the Townships.

The showers may persist into Wednesday morning. The mild temperatures Monday, will be replaced by much cooler highs in the single digits Tuesday on gusty northeast winds up to 50km/h.

Some clearing is possible on Thursday before another, even stronger fall storm approaches southern Quebec by Friday. This storm will produce heavy rain and strong winds, followed by very cold temperatures Saturday and even some snowfall across parts of southern Quebec and New England. Expect a widespread frost and freezing temperatures, even in urban areas by Sunday morning.

Hurricane Isaias made landfall around 8pm Friday night near Destin, Florida. Very strong wind gusts, in excess of 100mph (160km/h), resulted in widespread damage and power outages along the Florida Gulf Coast. Many homes lost there roofs, like the one above in Pensacola Beach. (Weather Nation)

Hurricane Isaias

Hurricane Isaias made landfall near Destin, Florida on Friday evening, resulting is significant wind damage and flooding. The hardest hit areas were across the western Florida panhandle from Pensacola west towards the Alabama border. Winds gusted over 100mph, producing significant structural damage and knocking power out to nearly one million residents across parts of Florida, Alabama, Mississippi and Georgia. 

Four deaths were blamed on the once Category 3 storm, the first hurricane in the Atlantic basin in 2026. Isaias weakened rapidly after landfall, but still had enough punch to spread heavy rain, thunderstorms and isolated tornadoes north into the Carolinas and Middle Atlantic region. 

October thunderstorms rattle around southern Quebec - Isaias first hurricane of 2026

The third thunderstorm in less-than 12 hours moved across the region early Thursday morning. The storms produced lots of lightning but no severe weather was reported. They were fast moving, resulting in just 5-10mm of rain on average across the Montreal area. (Valley Weather)

Several rounds of thunderstorms crossed the Montreal region over the last 24 hours. That included some rare nocturnal October storms just after midnight, that put on quite a sound and light show. The storms were fast moving, and outside of some vivid lightning and gusty winds, only 5-10mm of rain fell. Lightning strikes did manage to shut down the weather weary REM commuter trains to the south shore for several hours Thursday morning.

Just enough instability in the atmosphere will be present again Friday afternoon for perhaps another isolated, non-severe storm. Small hail and gusty winds will be possible. Otherwise high pressure will build into the region for Saturday and most of Sunday, resulting in fair skies. 

Temperatures will start the forecast cycle chilly, only reaching 13C (55F) Friday after morning lows near 5C (41). We can expect warmer highs both Saturday and Sunday as southerly winds develop between a Bermuda high off the Atlantic coast, and the remnants of hurricane Isaias moving north from the Gulf of Mexico into the Ohio Valley. The warm south winds will push highs close to 20C (68F) in Montreal.

By Sunday night and into Thanksgiving Day, clouds and perhaps a few showers will begin moving north across New England and into southern Quebec from what is left of Isaias.

NOAA image of Hurricane Isaias in the southern Gulf of Mexico late Thursday.

Hurricane Isaias

It has been a record-breaking quite hurricane season in the Atlantic basin to date, with only nine named storms and the latest we have had to wait for a hurricane to form. That record was set way back on October 7, 1905. It took until 7pm Wednesday evening for the first hurricane of the season in the Atlantic. Meanwhile the Pacific has recorded 19 storms, 9 of which have become hurricanes, 6 major storms, category 3 higher. The El Nino fueled Pacific hurricane season has resulted in over $682 million dollars in damage and 18 deaths.

Back to Isaias, as of Thursday evening the center of the strengthening storm was located in the Gulf of Mexico, 525 km south of the Mississippi River. The storm was moving northeast at 19km/h, with 160km/h winds, a category 2 hurricane. Isaias has prompted hurricane warnings along the Gulf coast from Florida to Mississippi. The storm should make landfall late Friday or in the pre-dawn hours Saturday, with a storm surge of 5-7 feet above sea level along the immediate coast.

Heavy rain, in excess of 150mm, will spread inland across the southeastern United States, north into the Ohio Valley.

That four-letter word is back across parts of Quebec - SNOW!

The calm after the storm on Friday, October 2. Morning rain and gusty winds gave way to a spectacular sky by day's end. (ValleyWeather)

A strong cold front has cut across the province early Monday morning, ushering in the coldest airmass of the season so far, on gusty northwest winds. High temperatures have been reached already, around 13C (55F), with the mercury expected to fall into the single digits, as low as 5C (41F) by Tuesday morning for Montreal. Along with the chilly air will be northwest winds in the 30-50km/h range. Parts of the province north of Montreal, including the higher elevations of the northern Laurentians may see the first snowflakes of the year, as well as the mountain peaks towards the Vermont border.

Don't panic just yet in Montreal, but now is the time to plan. I have my winter tire appointment booked already at Gordons in NDG, no point in avoiding the inevitable.  There is often a sharp contrast from September into October across Quebec and Ontario. September for the most part is just another summer month now. Weather conditions change rather abruptly in October, with the average high dropping from 16C (61F) at the start of the month, down to 9C (49F) by Halloween. Average lows drop to near the freezing point by months end.

More construction in Montreal as this ghoulish crew assembles a Halloween display on Ile Perrot. October weather is in sharp contrast to September, with frost, northwest winds and usually our first snowflake or two occurring. Time will tell what a Super El Nino October has in store for Montreal. (ValleyWeather)

This past September was not unusually warm, but we still managed an average temperature of 16.6C, which was 0.6 degrees above normal at Trudeau Airport in Montreal. September was very dry across the province of Quebec, with many regions running significant moisture deficits. Montreal measured only 50.6mm of rain, most of that falling on September 8-9. The long-term average is 89.2mm.

Montreal can expect a variable week, blustery and chilly to start, a brief warm up midweek, followed my clouds and cooler temperatures by Friday. Typical October weather for southern Quebec, with a vibrant mix of sun and clouds against the backdrop of vivid foliage that is starting to spread quickly. 

Clouds and showers are possible midweek, but no major weather systems are expected. The gusty northwest winds will likely prevent frost from forming in Montreal on Monday and Tuesday, but regions northwest of the city may see frost Tuesday morning.

Montreal remains on northwest edge of powerful Nor'Easter

A powerful Nor'Easter resembling a hurricane meanders off the east coast of the United States over the weekend. The storm produced widespread coastal flooding and damage from New England to North Carolina. (NOAA)

A powerful coastal storm has pushed clouds and showers into Montreal early Monday morning. The storm has been meandering off the eastern coast of the United States, hammering the region with high surf, strong winds and heavy rain. The coastal impacts have been significant, with widespread damage and flooding reported. Power is out to over 30,000 homes and businesses across the middle Atlantic and New England. Several regions including coastal New Jersey, Long Island and Hatteras Island, North Carolina have declared local states of emergency.

Ocean over wash across Highway 12 on Hatteras Island in North Carolina. Pounding surf over several days eroded the dune line an washed over the coastal highway. (NCDOT)

Successive high tides over the weekend, combined with pounding surf and winds over tropical storm strength, inundated coastal homes and roads. Highway 12 on the Outer Banks of North Carolina was washed out resulting in thousands of tourists being stranded. Emergency ferry service has been established, but the process is slow.

Here in the St. Lawrence Valley, we are seeing waves of light precipitation Monday morning, pinwheeling around strong low pressure located along the New Jersey coast. Monday will be a showery, chilly day in Montreal, with continued northeast winds, gusting up to 50km/h and a high of 16C (60F). Those winds pushed over 60km/h in parts of the region on Sunday, as we remained fully in the broad circulation of the east coast storm.

High pressure will settle into southern Quebec on Tuesday, accompanied by clearing skies. Temperatures will remain above normal in Montreal for most of the upcoming week.

A Nor'Easter before the first Atlantic Hurricane

A spectacular September sky as departing clouds play with the rising sun over Ile Perrot. The lowering angle of the fall sun allows for some beautiful sunrises and sunsets. (Valley Weather Photo)

Monday is the last official day of summer for 2026. I am still in shock the season is coming to an end, and stubbornly wearing shorts while waking my new pup on 6C mornings. I got to be me. While I absolutely enjoy all four seasons, summer is by far my number one. With that being said, fall arrives, like it or not, at 8:04 pm on Tuesday.

With that we are seeing much cooler nights in Montreal as daylight diminishes, along with an increase in morning dew, which will eventually become frost as we cool even more. The good news is that the weather looks spectacular in Montreal, with strong high pressure slowly drifting over southern Quebec for the entire week ahead.

As far as sensible weather is concerned, expect nothing but sunny, seasonable days and clear, crisp and cool nights. There is even a risk of frost across large portions of the upper Ottawa Valley as well as regions well north of Montreal. Frost advisories have been issued for those locations. Daytime highs will range from 16C (60F) up to 20C (68F) by Friday. Morning lows will be on the chilly side, ranging from 2C (36F) off the island of Montreal, increasing to 5C to 7C (40-45F) across metropolitan regions. 

Weekend Nor'Easter

As high pressure continues to suppress any significant weather well to our south this week, strong low pressure is forecast to develop along the Atlantic coast and move north towards southern New England by Friday night. This will be the first Nor'Easter of the young fall season, oddly occurring before the first hurricane in the Atlantic basin. It is a record-setting year, as our strengthening El Nino continues to put a cap on tropical activity in the Atlantic Ocean. We are still awaiting our first hurricane.

This year will be the latest on record for a hurricane to form, the previous benchmark was Hurricane Gustav on September 11, 2002. So far this year we have had only 6 tropical storms, including the current system, Fay, located 655km southwest of the Azores and weakening.

As far as Montreal is concerned, it appears the weather from next weekends potential storm should remain well south and east of the St. Lawrence Valley. Perhaps a few clouds, sprinkles and a chilly northeast wind on Saturday, but maybe nothing at all. Closer to the system, heavier rain, up to 50mm, strong winds and even some coastal impacts would be possible, but that will depend on the final strength and eventual track of the storm. Stay tuned, it's that time of year again.

Above normal temperatures expected for September

The rain stopped long enough last weekend for thousands of spectators to attend the annual car show in Hawkesbury, Ontario. The weather was perfect with light winds, low humidity, 25C and just a wisp of clouds. The perfect weather resulted in nearly 450 classic cars on display. It was a blessing after a summer where so many outdoor events have been rained out. (Valley Weather Photo)

The weather has been rather mild to start the month of September across southwestern Quebec, with indications that it will remain that way. We are at the start of what is expected to be an historic El Nino event, the warming of the waters in the equatorial Pacific Ocean. Typically this means a very moderate if not warm fall and winter season for Montreal and a large portion of Canada. Looking ahead, we can certainly see signals of milder-than-normal weather well into October for the Montreal region.

Warm high temperatures so far this month have reached the middle 20s. with lows remaining in the middle to upper teens. Warm southwest winds on Thursday have been gusting in excess of 60km/h. The wind managed to keep temperatures up overnight, with a low of 19C (66F) at Trudeau Airport. The normal high and low for early September is 20C (68F) and 10C (50F) respectively. We have not seen that, and shorts and t-shirts remain the clothing of choice.

We have managed some decent rainfall to start the month, with officially 49mm at Trudeau Airport, thanks in part to heavy showers on Wednesday evening that produce close to 30mm in just a few hours. I have recorded 44mm here on Ile Perrot.

High pressure will maintain sunny and mild weather well into the weekend, with the next chance of showers coming late Sunday.

Torrential rain on Labour Day weekend washed away roads, flooded homes and destroyed cars across Cape Breton Island in Nova Scotia. The storm resulted in one fatality and prompted a state of emergency across the region. Over 200mm of rain fell in juts a few hours. (Province of Nova Scotia)

It has been a very expensive summer for Canadians coast to coast, as storms and fires have resulted in billions of dollars in insured losses. The most recent storms in Toronto and Cape Breton, Nova Scotia have only added to the totals. In the Windsor storm, two tornadoes moving southeast for Michigan resulted in significant widespread damage to trees, cars, homes and businesses. The September 2 storm resulted in at least 1000 calls to public works for tree removal, 600 of those deemed urgent. Many fell onto homes and cars. The Toronto storm on September 1st, severely damaged Rogers Stadium, resulting in the cancelation of the AC/DC concert that was scheduled for September 16.

Last weekend, a torrential rainstorm dumped over 200mm (8 inches) on Sydney and parts of Cape Breton in Nova Scotia. Torrents of water washed away roads, damaged homes and resulted in one fatality. The damage from this storm alone will run into the hundreds of millions. With an El Nino fueled fall and winter season forecast, we can expect more of the same, with unusual weather patterns creating the potential for dangerous, damaging storms. 

Labour Day, the unofficial end to summer in Montreal

A tranquil weather moment from the heavens as the clouds part at sunrise this week in Montreal. It has been a challenging summer as far as the weather is concerned from coast to coast, with searing heat for some, drought, fires and floods for others. The increasing strength of the current El Nino is sure to make this fall and winter forecast just as challenging to say the least. (Valley Weather)

Labour Day weekend is upon us, typically the unofficial end to summer. This was more of a reality in my youth, as the weather typically turned cooler much quicker and school rarely started until after the last long weekend of the summer. Things has changed considerably these days as most schools are already back in session, and summer warmth tends to drift well into September and in some cases even early October. 

The weather this weekend looks ideal for outdoor activities. Scattered showers are possible Saturday as a stubborn upper level low remains to our northeast, but the day should not be a washout. Sunday and Monday will feature nothing but sunshine, with daytime highs rising into the middle 20s and overnight lows in the low teens. 

You can definitely feel summer slipping way as the longer nights tend to produce a heavier dew in the mornings, as well as fog in places. Overnight low temperatures can easily find their way into the low teens. The trees are also beginning to respond to the shorted amounts of daylight, which typically begins the leaf changing process, despite how warm it is.

It was Toronto's turn this week to join Montreal and Ottawa in the summer of the flood. A powerful thunderstorm on Wednesday afternoon resulted in close to 140mm of rain falling in less than one hour, flooding residents, highways and underpasses across parts of the city. (Toronto Tourism) 

Toronto's 100 Year Storm

It has been the summer of fire and flood across Canada. You can now add the Greater Toronto Area (GTA) to the growing list of communities impacted by significant flash flooding events. Powerful thunderstorms on moved southeast off Lake Huron Wednesday afternoon, racing across the Toronto and Niagara regions and into western New York.

The storms produced widespread wind, hail and flooding, resulting in significant damage  as well as power outages to more than 150,000 homes and businesses. Wind gusts were observed up to 91km/h at Brantford and 83km/h at Pearson Airport. Major damage was reported at Rogers Stadium. Hail as large as 2.5 to 6.5cm punched out windows in homes and cars in North York. Several motorists had to be rescued after 139mm of rain fell in Caledon, with 133mm at Vaughan. A tornado was reported near Bamberg, northwest of Kitchener.

Severe thunderstorms on Thursday resulted in significant damage across this east Windsor, Ontario neighbourhood. (Photo: @onlocation.tv)

On Thursday another round of strong thunderstorms moved across southeast Michigan into the Essex/Windsor area. The powerful storms and possible tornado tore the roof off at least one home spreading debris across the east Windsor neighbourhood. Large, mature trees were uprooted, many landing on homes and cars or blocking streets. Once again large hail and torrential rain fell as well. The Northern Tornadoes Project out of Western University in London will be investigating the storm dame Friday. They suspect based on radar and reports from neighbouring Detroit, that two tornadoes may have impacted the area between Windsor and Amherstburg.