Heat warning in effect for Montreal

The high of 32.1C (90F) at Trudeau Airport Friday afternoon, narrowly missed the 1970 record by one tenth of one degree. We have a good chance at beating both record highs this weekend. Humidex values reached 40C during the late afternoon hours Friday, and will likely do so again on Saturday and Sunday. A heat warning is in effect for the St. Lawrence Valley.

UPDATE: 8AM WEDNESDAY, AUGUST 25: Montreal can expect another hot and humid day today, with the heat warning still in effect for southern Quebec. The heatwave has entered its sixth day, but there is some relief on the horizon. The high temperature Wednesday will be in the low to middle 30s once again, with humidex values approaching 40C this afternoon. There is a slight chance of a shower or thunderstorm tonight and again Thursday afternoon.

Thursday will be the last day in this current heatwave, with another daytime high of 33C forecast and very humid conditions in advance of a cold front. That front will move southeast across the St. Lawrence Valley late in the evening hours, followed by cooler and less humid air. The temperature will fall into the middle 20s for highs on Friday, with overnight lows in the middle to upper teens.

Just a little bit of natural air conditioning to provide some relief in what has been a scorching stretch of weather. In the last week alone, Montreal's Trudeau Airport has set a dozen new records related to maximum high and low temperatures as well as maximum humidex and dew point readings.

UPDATE: 8AM, TUESDAY, AUGUST 24: It is yet another steamy morning in Montreal, with a heat warning in effect and a current temperature already at 24C (76F). Humidex readings will once again approach 40C in the St. Lawrence Valley this afternoon. We managed another record warm day on Monday, reaching 31.1C (88F), tying the record set in 1947. It was the third consecutive record-breaking day in this stretch, and the 19th day of 30 plus temperatures this year. We are somehow closing in on the record of 24 days set just last year, however we may run out of summer before that happens. 

Tuesday will be hazy, hot and humid once again, with a high of 31C (88F). After a muggy overnight low of 23C (73F), the temperature Wednesday will rise to 33C (92F). The heat will persist through Thursday, with a high of 30C (86F) forecast, before a cold front delivers a few showers, but more importantly a cooler and less humid airmass by Friday.

Previous Posts:

UPDATE: 8AM, Monday, August 23: The heat warning remains in effect for Montreal, southern Quebec and Ontario. We continue to set all kinds of temperature and humidity records this August. After a cool July, August has delivered mid-summer heat. Sunday was no different in Montreal, with a high of 32.4C (91F), smashing the previous benchmark of 30.6C (87F) set in 1955. We also set the record for the warmest overnight temperature, dropping to only 24C (76F) at Trudeau Airport Sunday morning.

Sunday was the 9th day this month with high temperatures over 30C, with 18 now for the year to date. After a July with only one 30C day, I never thought we has a chance at the record of 24 days set just last year, but here we are. Above normal temperatures are forecast for the rest of this week so we should add to this total. There should be a break in the heatwave by late Thursday or Friday.

We desperately need rain as only 19.8mm has fallen in Montreal this month, which is way below the long-term average of 94.1mm. There is only a slight chance of a hit and miss shower or isolated thunderstorm through Thursday. Let's hope it's more hit than miss as has been the case most of this summer in the metropolitan Montreal region. Stay cool! 

7AM Update - Sunday, August 22: A heat warning remains in effect for southern Quebec, as the entire region remains under a very warm, humid tropical air mass. Montreal had a record high of 34C (94F) on Saturday, with humidex readings into the low 40s. The weather may be a degree or two "cooler" today as high clouds from hurricane Henri drift overhead. The weather will still be muggy, with a high of 32C (90F). The record high for Sunday is 30.6C set in 1955, so we should establish another record today. Morning lows were very warm as well, 24C (76F) in Montreal.

Previous Post: A heat warning is in effect for the St. Lawrence Valley, southern Quebec, eastern Ontario and the Champlain Valley of New York and Vermont. Stay hydrated, wear light clothing and avoid strenuous outdoor activities. Seek air conditioning if possible.

Summer refuses to yield to cooler weather, as we are in the midst of another August heatwave. Hot and humid air has settled over southern Quebec and Ontario for the weekend, fueled by strong high pressure located off the Atlantic coast. This Bermuda high is pumping tropical air northward into our region. Adding to the moist, steamy air mass is the northward track of tropical storm Henri.

Saturday will be hazy and hot in Montreal with a high of 33C (91F) forecast and humidex/heat index values into the low 40s. Sunday will be similar, with a high of 32C (90F), but with some high clouds streaming northward form Henri, as the storm makes landfall on Long Island, New York and moves into southern New England. There is a risk of perhaps a few showers along the US border late Sunday as well as a wind shift to the northeast in the afternoon. At this time little other impacts are expected in Quebec, with Henri forecast to move northeast after landfall, well south of Montreal.

In terms of high temperatures for Montreal this weekend, we have a chance at exceeding the long-standing record highs for both Saturday and Sunday. The record high for both days was established in 1955, 32.8C Saturday and 30.6C Sunday.

Tropical Storm Henri

Henri was located 315km southeast of Cape Hatteras, North Carolina at 5am Saturday morning, with 110km/h winds. Henri is expected to strengthen into a hurricane on Saturday, while maintaining a northward track. Widespread watches and warnings have been posted for the northeastern US and southern New England including metropolitan New York City. Rainfall of up to 250mm, along with a storm surge of 3 to 5 feet is expected. The storm is expected to make landfall on central Long Island during Sunday afternoon. The center will then move inland across far western Massachusetts before moving northeast into Maine. The path of Henri will have to be watched closely to see what impacts if any we can expect locally. It appeared earlier in the week, that Henri was moving out to sea. Since then, each successive forecast model run has moved the storm closer and closer to an expected US landfall close to New York City.

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