A battle of the seasons - flood risk lowering for Montreal

Despite water levels lowering on the Ottawa River this weekend, pumps will remain in place in Sainte-Anne-de-Bellevue and other municipalities until the threat is over. (Valley Weather)

The weather was anything but May-like on Saturday across southwestern Quebec, with a cold northwest wind, chilly temperatures and even some sleet and graupel falling from the sky. An upper air disturbance produced enough instability to generate a few lightning strikes early Saturday afternoon. Temperatures remained quite chilly throughout the weekend, with scattered frost reported. Highs were in the 9C to 12C range (49-54F), with low temperatures a few degrees either side of the freezing point.

Early Monday morning, we have milder air trying to work into the region, accompanied by some robust showers along a warm front. That front should clear the region by noon, allowing for a few breaks and gusty, warm southwest winds. Temperatures should warm into the upper teens and even a fews 20s around. The same can be expected for Tuesday, before a cold front sweeps across eastern Ontario and southern Quebec.

That front will produce a few showers and even a thunderstorm, before a soaking rain develops into Wednesday. Temperatures will fall back to the single digits for highs on Wednesday, as the seasons continue to battle across most of Canada.

The weather was cold enough for sleet to fall over the weekend in parts of southern Quebec. (Valley Weather)

Spring Flooding

The news is better concerning the ongoing spring flood potential. Pumps and dikes remain in place, but most roads have been reopened as water levels continue to drop along the Ottawa River and Lake of Two Mountains. Over 100mm (4 inches) of rain fell in April across the region, allowing for water levels to rise sharply late last month. Since May 1st, another 5-10mm has fallen, with 15-20mm possible this week. That being said, water levels remain stable in the Ontario portions of the river and are even lowering in some cases. The end result is that mitigation and observation efforts will remain as is for most municipalities in the greater Montreal area, but the forecast looks favourable at this time for a continued drop in in levels.

The gauge at Sainte-Anne-de-Bellevue remained in minor flood stage Monday morning, at 23,83 metres and slowly rising. However most other gauges on other portions of the Ottawa River upstream from Montreal are showing levels stable or even lowering.

Over the weekend the bridge to Île Mercier was reopened, as was Chemin de l'Anse à l'Orme late last week. Both had been clsoed since mid-April after being inundated by high water from Rivière des Prairies.

A second wave of high water possible for Montreal

Flood waters in Vaudreuil/Dorion and across southwestern Quebec have been lowering over the last week. However upcoming wet weather may force another surge of water down the Ottawa River towards Montreal over the upcoming week. (Photo: Ledy Quintero)

Flood warnings are in effect across the Ottawa River on the Ontario side of the border, as another wave of rising water is expected. The flood watch has remained in effect on the Quebec side from Pointe Fortune to Montreal. The recent dry weather has allowed water levels to drop across the region, but that will change with more rain in the forecast along with melting snow from the northern portion of the basin.

Water levels at the gauge in Sainte-Anne-de-Bellevue have dropped from 23.94 metres a little over a week ago down to 23.80 metres currently. This is back into the minor flood stage. 

Concern is on the rise that we may see another wave of high water throughout the Ottawa River Basin and its tributaries into the first week of May. Our dry weather is set to com to an end on Wednesday, with rainy weather forecast as a frontal boundary moves east. Both Ottawa and Montreal are forecasting 15-25mm of rain over the next 36 hours, with some regions in the Ottawa Valley expecting as much as 50mm.

Thankfully all flood mitigation efforts remain in place, with municipalities remaining vigilant and on high alert. It has been a welcome relief over the last week or so to see water levels lower in the Montreal region. The hope is that water levels will not reach those of earlier this month along the Ottawa River and Lake of Two Mountains. 

Our weather will not only turn wet, but sharply colder Thursday into the weekend, as an upper level low drifts over the region. Temperatures will remain in the single digits for highs through the weekend. Overnight lows will be close to the freezing point, with even a few flurries and scattered frost possible for some locations. 

One group that is happy to see some wet weather is SOPFEU, Quebec's wildfire management agency has been dealing with tinder dry conditions in our forests. Despite the flood threat, many regions have had very high fire danger, with burn bans in effect for several municipalities. The wet weather should alleviate that threat for the short-term.

Spring flooding continues across the Montreal region

A flooded boathouse along the shores of Lake of Two Mountains in Sainte-Anne-de-Bellevue. Water levels remain high, with some flooding observed, but so far things remains stable. The next two weeks will be critical as to the extent of flooding this sprung. (Valley Weather Photo)

The flood watch remains in effect for most the Ottawa River Valley, including parts of the metro Montreal region.

Water levels are stable early Thursday morning, thanks in part to the dry weather across southern Quebec. The Ottawa River remains in moderate flood stage, with levels similar to those of 2023, but still below the devastating record-setting flooding in 2017 and 2019.

Lessons learned by municipalities during both those major floods are being applied in 2026, and so far those efforts are holding. Pallets of sandbags and pumps have been placed in many locations from Pierrefonds to Vaudreuil. Mitigation and protective measures will remain in place for the foreseeable future.

The raging Sainte-Anne Rapids under the Galipeault Bridge looking west at Saint-Anne-de-Bellevue on Tuesday evening. The water levels at this location are in moderate flood stage, at 24.19 metres Thursday morning. (Valley Weather Photo)

On Thursday, Vaudreuil placed a protective barrier along Boulevard Saint Charles to protect the road and adjacent dwellings from the advancing Lake of Two Mountains. Pumps are working 24/7 in that community as well as Sainte-Anne-de-Bellevue to help keep storm sewers from backing into nearby homes.

Municipalities, such as Sainte-Anne-de-Bellevue, are pumping water from storm sewers 24/7 to help alleviate any back flow into nearby homes. (Valley Weather Photo)

The Lake of Two Mountains at Sainte-Anne-de-Bellevue was at 24.19 metres Thursday morning, in moderate flood stage, but lowering slightly. Pointe-Calumet was at 24.27 metres, minor food stage for that locations and stable.

Water levels are also stable at this point northwest of Montreal across the eastern Ontario. The forecast remains favourable for water levels, as no rain is forecast though Sunday. Cooler temperatures will also slow down melting where snow cover still exists across the northern portion of the basin.

So far in April, Montreal has has 89.1mm of rain, with Ottawa at 90.9mm. 

From summer to winter in 24 hours - flood risk increasing across metro Montreal region

Water levels in Vaudreuil are on the rise late Sunday afternoon, with minor flooding being reported in areas close to the shore of Lake of Two Mountains. The municipality completed installing pumps over the weekend to help prevent backflow into the stormwater system. (Valley Weather)

A flood watch remains in effect across eastern Ontario and southern Québec, as water levels along the Ottawa River and it's tributaries continue to rise. The station at Sainte-Anne-de-Bellevue reached moderate flood range, Monday, sitting at 24.00 metres. Water from the Lake of Two Mountains has starting creeping over the jetty near the boardwalk.

Flooding has also forced the closure of Chemin de 'Lanse-A-l'Orme from Senneville Road to Tiberlea Trail along the Senneville/Montreal border. Flooding has also occurred on Ile Mercier, threatening Louis Roch Street.

You can add Vaudreuil/Dorion to the list of municipalities preparing to fight the advancing Lake of Two Mountains. Public works have been installing pumps along Saint Charles in Vaudreuil to help prevent any backflow in the stromwater system. A dike was also installed at the end of Hotel-de-Ville Street as a preventative measure.

The good news at this time is that weekend precipitation proved to be less than forecast, with only 8mm of rain and a trace of snow falling at Trudeau Airport. Lake levels remain well-below those observed in both 2017 and 2019. Late Sunday afternoon, levels were reported as being stable, but they are forecast to rise slowly through Tuesday.

The strong cold front that moved across the Montreal region Saturday night, dropped temperatures from summertime warmth on Saturday back to near the freezing point Sunday morning. Montreal reached 23C (73F) Saturday, with some southwestern Quebec locations pushing 25C (77F). Gusty southwest winds reached close to 70km/h. By Sunday morning, the temperature had plunged to 2C (36F) in Montreal, with light rain mixing with and changing to light snow. Monday morning was even colder, with 0C (32F) at Trudeau Airport.

The week ahead looks chilly, but with little in the way of precipitation expected through Friday. Hopefully this will allow rivers to crest across the region and begin lowering.

Metro Montreal region under a Level 3 Flood Watch

Water levels along the Ottawa River on Ile Perrot are on the rise Thursday afternoon, in response to a wet April to date, as well recent ice and snowmelt across the region. A flood watch remains in effect for Montreal. (Valley Weather Photo)

"We have just come up to Level 3, which is the highest level of emergency the city can bring it up to" Montreal Mayor Soraya Martinez Ferrada.

A Level 3 Flood Watch is now in effect for Montreal - allowing for the mobilization of personnel, material and resources in the event of flooding.

Municipalities across the Island of Montreal, Laval and up and down the Ottawa River Valley are in flood watch, as waters levels continue to rise. Many parts of eastern Ontario and southwestern Quebec have had a very wet spring to date, with rainfall closing in on 75mm at Trudeau Airport since April 1. At this time the St. Lawrence River and Lac St. Louis are stable and below flood stage.

Municipalities like Senneville and Sainte-Anne-de-Bellevue on the western tip of the island are in flood watch mode as water levels continue to rise along Lake of Two Mountains. Pierrefonds as well as parts of Laval are also watching water levels rise. (Valley Weather Photo)

The gauges on Lake of Two Mountains at Sainte-Anne-de-Bellevue and Terasse Vaudreuil are at 23.50 metres, or about 200mm (8 inches) above minor flood stage. Water levels have stabilized at both locations for today but are expected to rise slowly in the coming days in response to higher water levels upstream. Pointe Calumet is at 23.58 metres and rising. Minor flooding has been observed.

Montreal and the Burroughs will be monitoring the levels 24/7 at the cities emergency operations centre for the near term, ready to provide assistance as needed.

As far as the forecast goes, the city remains under a special weather statement for the potential of more heavy showers through Sunday. Rainfall amounts of 15-25mm are possible. The good news is that Saturday looks dry now, and cooler, drier weather next week may slow down runoff and water levels.

Across the province, 12 rivers are in minor flood stage, while 17 more are on the rise, and being monitored. Vigilance will be important over the next week as water levels fluctuate. At this time, we are not expecting to reach the record levels and subsequent flooding that occurred in both 2017 and 2019.

A strong cold front will push across southern Quebec on Saturday night accompanied by showers and maybe even a rumble of thunder. Sunday looks much colder, with temperatures falling from highs in the low 20s (70F) Saturday, down to 5C (41F) Sunday. Montreal will likely drop below freezing into Monday morning, -3C (27F), and I can't rule out a stray snowflake or two.

April showers bring May flowers...and spring flooding

Rainfall over the last 72 hours has dropped 30 to 35mm across southern Quebec. The rain along with melting snow and ice has resulted in sharp rises in area rivers. Several are approaching minor flood stage. Vigilance is important over the next few weeks, especially if you live along or near  flood prone areas of southern Quebec. More rain is forecast over the next three days in Montreal.

It is that time of the year again where we hold our breath as rapid snowmelt and spring rain swell our rivers. During the past two weeks across our region, most of the ice has melted away from both the Ottawa and Saint Lawrence Rivers as well as the tributaries in and around southern Quebec. This combined with rainfall this April has resulted in sharp rises in the rivers that surround our island as well as Laval.

Since April 1st, 72.4mm of rain has fallen at Trudeau Airport. Rain has fallen on 12 of the 14 days this month, with more forecast over the next 72 hours. Sécurité Publique Québec has been monitoring the gauges around southern Quebec and reports one in medium flood stage, 7 at minor stage and 18 under surveillance.

Parts of the Mille Îles River are reporting minor flooding, while the gauge in Lake of Two Mountains at Sainte-Anne-de-Bellevue is reading 23.28 metres, just below minor flood stage. Most rivers are slowly rising, with the next 72 hours being critical as to where we go from here. North of Montreal, the Ouareau River near Rawdon is in moderate flood stage.

A wavy stationary front stretching from Iowa to Maine, has been the focus of rain and strong thunderstorms at times. The front lies southwest of Montreal, keeping very warm and humid air just to our south. Most of the storms have been firing up along and south of the front in southwestern Ontario and New England. The front is separating summer from spring, with Windsor, Ontario reaching 27C (81F) on Tuesday afternoon, while Montreal struggled to reach 9C (49F). As I write this blog, Montreal is siting at 7C (45F), while New York City is currently 28C (83F).

Several areas of low pressure will ride along the front producing more showers and thunderstorms through Sunday, with another 15-25mm of rain possible. A cold front will sweep across the region late Sunday, ushering in unseasonably cold air for a day or two. There may even be some flurries around.

Residents across the metro Montreal region who live in flood prone areas adjacent to our rivers, should continue to monitor water levels and listen to information supplied by your burrough or municipality.

Has spring finally sprung in Montreal?

Barring any surprises, Wednesdays snowfall of 1-2cm should be the last of the winter season here in Montreal. (Valley Weather Photo)

Montreal managed a breezy, warm high of 16C (61F) at Trudeau Airport on Thursday, with the mercury inching past 20C for some southwestern Quebec locations. I must admit, it felt good. The final traces of snow have melted away and the cleanup of our fair city has begun.

What could be the final snow of the season, barring any big surprises, put down a centimetre or two on Wednesday. That melted away quickly, but it was enough to create some areas of black ice and several serious collisions. One incident closed the Ville Marie Tunnel eastbound while yet another snarled the Mercier Bridge. You are reminded that despite the warmer weather, we often dip to or below the freezing pint at night in April, so treat any standing water like ice.

In terms of the future, we are looking at a cold front approaching southern Quebec on Friday, with rain expected ahead and along the front. As much as 10-20mm is possible. Temperatures are mild Friday morning, but will dip as the day moves along. Some wet snow may mix in well north of the city and across the Ottawa Valley.

The weekend looks like typical early April weather, with fair skies and highs in the low teens. Another front will bring rain to the region Monday. Next week looks warmer and wet. We may see significant amounts of rainfall over the next week or so.

Looking back at March, Montreal (Trudeau) received 33cm of snow and 45.9mm of rain, including lots of freezing rain. Winter 25/26 has hopefully drawn to a close, with the seasonal total for snow sitting at 213.6cm (84.1 inches).