Weekend to Bring A Break From The Heat

Slightly cooler weather will move in this weekend behind a low pressure system forecast to move through tonight and tomorrow. In addition to the cooler temperatures, this system will bring a chance of rain and thunderstorms to the Red River Valley.

Tonight & Tomorrow

Friday

27°C / 18°C
Increasingly cloudy; risk of a thunderstorm late in the afternoon into the evening. Humid.

We’ll see gradually increasing cloud today as the surface trough associated with a low pressure system pushing into the northern Interlake approaches. There may be some ongoing thunderstorm activity along the trough this morning as it pushes through SW Manitoba and that threat will move eastwards into the Red River Valley by the late afternoon or early evening. A southerly wind ahead of the trough coupled with a capping inversion will draw moisture northwards once again and trap it near the surface, making for another hot, sticky day here in Winnipeg. Our high temperature will only climb to around 27 or 28°C, though, thanks to the increasing cloudiness through the day. That hot, humid weather will bring the threat for thunderstorms – potentially severe – late in the afternoon into the evening hours. At this point, it seems like somewhere between 8PM and 11PM seems like the most likely time for seeing any potential storm activity. After that we’ll see our temperature drop to around 18°C under a partly cloudy sky.

Saturday

25°C / 12°C
Becoming cloudy, good chance of showers or thundershowers. Humid again.

Saturday will be another humid day as we remain in the moist air mass ahead of the cold front. We’ll see a fairly good chance of showers or thundershowers beginning later in the morning and through the afternoon. Skies will start off as a mix of sun and cloud but should become fairly cloudy in the afternoon as things become more unstable with the approaching cold front. We’ll see a high of around 25°C which will mark the last day in our hot, muggy air mass. The threat for showers or thunderstorms will persist until the cold front passes.

500mb Winds for Saturday Afternoon

500mb winds forecast by the NAM show an intense upper-level low pushing into Southern Manitoba which may be the catalyst for showers and thunderstorms on Saturday afternoon and evening.

The cold front will push through overnight, bringing northwesterly winds that will clear out much of the moisture and drop us to a comparatively cool 12°C for an overnight low with clearing skies.

Sunday & Holiday Monday

Sunday

23°C / 8°C
Sunny. Cooler and much less humid.
Monday

25°C / 13°C
Sunny and warm.

Sunday and Labour Day Monday look absolutely beautiful. Sunday will be slightly cool with a high of only around 23°C and lead into a chilly night with a low dropping into the single digits bottoming out around 8°C. The heat starts to return on Monday with sunny skies continuing as we climb to a mild 25°C.

The Trend Next Week

Looking further into the week, it looks fairly nice overall as the upper ridge begins rebounding back northwards into the Prairies. Highs will push back into the upper 20’s with humidity staying fairly low until late in the week. Things look fairly dry through the first half of the week, with a few weak disturbances bringing the threat for isolated-to-scattered thunderstorms late in the week. For the most part, though, it looks to be a beautiful, warm week. Summer may be late, but it doesn’t look like it’s going anywhere soon!

Unsettled Weather Pattern Developing

After a couple slightly cooler days across Southern Manitoba the heat is set to return as a southerly flow develops ahead of a upper trough pushing towards the Rocky Mountains. Unlike the potent upper ridge of earlier this week, this southerly flow will be peppered with disturbances ejecting northeastwards out of the west coast trough and we’ll see substantially more unsettled weather over the next week or so.

Today

Friday

30°C / 20°C
Sunny & increasingly windy. Chance of thunderstorms & increasing humidty overnight.

We’ll today start off pleasantly as we head towards a high of about 30°C, however by midday the winds will begin pickup up out of the south and will likely reach 40–50km/h with gusts as high as 70km/h by the end of the day, making it not quite as pleasant as 30°C can be. We’ll see a mix of sun and cloud as well as some mid-level cloud streams up from the southwest through the day. Fortunately it looks like the worst of the humidity will stay off to our south for the day and, with dewpoints only in the low teens, will help the day be a little more comfortable.

There will be a chance of thunderstorms overnight into the morning hours on Saturday though as the first of many impulses lifts northeastwards into Southern Manitoba, dragging up with it substantial amounts of humidity. Overnight we should see our dew point climb to nearly 20°C, which means we’ll only see our overnight low dip to close to that mark[1]. Regarding the thunderstorms, at this point it looks like the greatest threat for any activity will be over SW Manitoba then arcing NE through the Interlake region. There will be a chance of a thunderstorm through much of the Red River Valley, with the greatest risk at the north end – Winnipeg in particular could end up seeing the bulk of the action if things end up just a bit further south than currently forecast – and a decreasing risk towards the U.S. border. These storms are not expected to be severe, however given the ample moisture that they will be feeding off of, any storms that develop could produce substantial amounts of rainfall in short periods of time.

Saturday

Saturday

32°C / 18°C
A mix of sun and cloud; risk of thunderstorms in the morning and then the afternoon.

Saturday will start off cloudy, potentially with showers or thunderstorms in the region, and then begin gradually clearing. It will be very humid in the Red River Valley, with dew points in the low 20’s. We’ll climb towards a high of around 32°C which, with the humidty, will feel much more like 37–40°C. In the afternoon a sharp dryline[2] will begin working it’s way eastwards into the RRV associated with drier, westerly winds.

Thunderstorms are possible by late afternoon, but the exact location of them will depend on the entire synoptic setup and the placement of the dryline, which will be the feature that the storms will develop along. At this point, it appears that the western half of the RRV will be safe with an increasing risk through Winnipeg & the central RRV to a much greater chance over the eastern RRV into Sprague & the Whiteshell. These storms could easily become severe given the ample heating and surface moisture, 500mb jet core in the area providing 30–40kt of bulk shear, as well as a defined trigger in the dryline.

The storm potential does seem fairly dependant on the exact placement and strength of the dryline; if it doesn’t evolve to be strong enough or hangs back too long or blows through too early, then there will be almost no chance of any storms on Saturday. If storms develop, the main threats (particularly if they become severe) will be torrential rain and large hail. A tornado could not be ruled out either, but the flow may not be strong enough to support/sustain one. Strong winds would not be a widespread concern at this point.

And of course, since there has to be one more wrinkle in things, this will all be dependant on mid-level temperatures. The Canadian long-range model (GDPS) is forecasting cooler air at the mid-levels pushing over the RRV on Saturday afternoon, which would help destabilize things; if temperatures remain warmer at the mid-levels then we would likely remained capped and see have no thunderstorm activity. A lot of words for a conditional threat, but it could be a significant severe thunderstorm day for the Red River Valley and the Whiteshell, so I thought we should go over some of the possibilities and unknowns!

Sunday

Sunday

32°C / 18°C
Mainly sunny.

Sunday will be a very nice day with mainly sunny skies, light winds, and a high near 32°C. There will be little to no chance of any precipitation; at this point it looks like there may be a marginal chance of an isolated thunderstorm near the U.S. border in the Red River Valley, but even that is pretty unlikely. Humidity will actually be quite comfortable as well, with dew points in the low teens. Probably the nicest day of the weekend, so get out there and enjoy it!

Next Week

Without spending too many words on it, next week continues the warm trend with highs looking to be near 30°C much of the week; we’ll also see multiple disturbances move through bringing showers and thunderstorm threats to Southern Manitoba. It will likely be more pleasant than not, though, and our late-arriving summer will certainly continue!


  1. The dewpoint is often a good measure of what overnight lows will be as the temperature will often – but not always – dip just a couple degrees below it. When the dew point is high, such as the upper teens or low 20’s, often the temperature will only approach the dew point temperature, not dip below it.  ↩
  2. A dryline is similar conceptually to a warm or cold front, but instead of being warmer or colder on one side of the front, it’s more humid ahead of the dryline and substantially drier behind it.  ↩

Hottest Weather So Far This Year Ahead

The warmest weather we’ve seen all year is shaping to move in today and persist through the next week as a upper ridge begins to build in over the Prairies. The heat and humidity will be here in full force with daytime highs climbing over 30°C and dew points climbing into the upper teens or even perhaps the low 20’s.

Friday

30°C / 15°C
Mainly Sunny
Saturday

33°C / 17°C
Mainly sunny with a slight risk of a late day thunderstorm.
Sunday

30°C / 17°C
Mainly Sunny

We’ll see beautiful sunny skies today as our temperature climbs to around 30°C. The humidity will become more noticable as the day wears on as the dew point climbs from the low teens to around 17 or 18°C. Temperatures will drop to around 15°C tonight under clear skies.

Tomorrow looks to be a scorcher of a day. The temperature will climb into the low 30’s with high humidity as the dew point climbs over 20°C. It will feel closer to 38–40°C by the afternoon as the Red River Valley bakes in the warmest temperatures of the year. A disturbance will be moving through the Interlake region that will bring a very slight risk of a thunderstorm late in the day, although at this point it looks like most of the activity will stay north of the Red River Valley. Beaches along the South Basin of Lake Winnipeg will have a greater chance of seeing thunderstorm activity than we will here in Winnipeg, so if you’re planning on camping north of the city, that may be something to keep in mind. We’ll have updates below in the comments on the thunderstorm potential tomorrow. We’ll head to an overnight low of aroun 17 or 18°C Saturday night.

Sunday also looks to be a gorgeous day. The hottest weather will be off to our east, but we’ll still see temperatures climb to around 30°C under sunny skies. There will be more of a westerly component to the winds which will help flush out some of the humidity through the day.

Next Week

Next week looks to keep the heat. While the upper ridge flattens thanks to a couple disturbances that move through on the weekend, it’s set to rebound by mid-week, which will keep our daytime highs in the upper 20’s or low 30’s for what looks like the entire week. At this point it looks like we may see some showers or thunderstorms on Monday evening/night, but after that current indications are that it will be hot and dry for the remainder of the week.

After 4 weeks of below-normal temperatures, get out there and enjoy the heat wave! Just be sure to practice some heat safety and wear hats and drink plenty of water. Have a great weekend!

Summer Returns!

After weeks of below-normal temperatures in Winnipeg, we can finally rejoice as summer is set to make a significant return.

Wednesday

25°C / 13°C
Mainly sunny
Thursday

28°C / 14°C
Mainly Sunny
Friday

30°C / 17°C
Mainly Sunny

Describing the next few days will be short and sweet, we’ll see mainly sunny skies, a warm-up returning us to summer-like temperatures and increasing humidity as Gulf moisture is advected northwards in a southerly flow.

The only significant weather to speak of will be a slight chance of a shower or thundershower in the southwest Red River Valley on Thursday morning as a weak area of convection pushes through North Dakota. Other than that slight chance, things should be fairly dry through the rest of the week as well.

The Weekend

This weekend looks exceptinally summer-like as a humid, Gulf-sourced air mass entrenches itself over the Red River Valley. With temperatures in the low 30’s and dew points climbing to nearly 20°C, it’s going to feel more like it’s closer to 36 or 37°C. There will be a slight chance of showers or thunderstorms on Saturday night, but at this point the threat seems marginal at best. It looks to be a dry weekend for the most part with variable cloud cover.

After the weekend we move into a slightly dryer air mass, but the heat sticks around with daytime highs looking to be in the upper 20’s through most of the week.