Prairie Weather This Week – Midweek Update Sep 4

Prairie Weather (Rural Roots Canada) – Strong wind storm Saskatchewan. Favourable harvest weather. Frost risk.

Farmers in southern Saskatchewan are dealing with a major windstorm today (Thursday), with gusts up of 80 to 90 km/h. The wind will die off this evening. Visibility already reduced by forest fire smoke, may be further impacted by blowing dust. After the windstorm ends, conditions in Saskatchewan will improve, and all three provinces are expected to enjoy favourable harvest weather.

Here’s a color-coded Harvest Risk Table for Sept 4–7, 2025.

Green = Low Risk (good for harvest)

Gold = Medium Risk (mixed conditions)

Red = High Risk (poor conditions, likely delays)

Before looking at the daily details, here’s a bit of background on what’s going on with our weather. The animated map below shows the upper level wind and pressure pattern. Hang on…this’ll get a bit more interesting…

The Big Blue Blob that drops into the United States through Manitoba and Ontario is dragging a powerful cold front with it, and generating all that wind in Saskatchewan Thursday. To the west, you see oranges over BC and Alberta. That’s an upper level ridge that brings dry, warm weather to the west. Under the ridge, Ashcroft BC on Wednesday reached a high of 40.7. That’s the highest temperature ever recorded in September in Canada. The low to the east (Big Blue Blob) is drawing cool, northern air into Saskatchewan and Manitoba, while Alberta heats up.

If this was, say, anytime in December, January, or February, the Big Blue Blob would represent extraordinarily cold air. And, media headlines would be sure to include “POLAR VORTEX!” That’s a topic for another day.

Thursday

Alberta

As mentioned, upper level high pressure over BC extends into Alberta. That will keep the province under a clear sky, though visibility and sunshine will be reduced by forest fire smoke. In the afternoon, there is a chance of a shower or thundershower over the foothills, though the smoke may suppress convection, and kill the storms before they’re allowed to develop. For Thursday, the hot weather stays in BC, and in Alberta, we can expect highs of 15 to 20.

Saskatchewan

As mentioned above, a strong wind storm will impact southern Saskatchewan, with gusts of 80 to 90 km/h. Equipment should be secured. The wind won’t die down before evening. Rain will fall along and near the Manitoba boundary, with totals of 25 mm. In Western Saskatchewan, highs will only reach the low teens. With the strong northerly wind in central and eastern Saskatchewan, highs at best will reach the low double digits. It will be windy, cold, and wet through much of the province, and, needless to day, it’s a very poor harvest day.

Manitoba

Cold, wet weather can be expected as the Big Blue Blob (see above) marches across the province from north to south. It will be a poor harvest day with strong wind, significant rainfall, and cold weather. In much of Manitoba, highs could end up in the 5-10 degree range. It will feel like fall.

Friday

Alberta

The upper ridge continues to build into Alberta, and it will be another day of excellent harvest conditions. All day long, the sky will be sunny, and the wind light. South of Edmonton, and east of highway 2, it will be quite cold in the early morning, with lows between 0 and 5. In the afternoon, highs across the province, are expected to reach the low 20s, though forest fire smoke may inhibit the warmth.

Saskatchewan

There is a slight risk of frost in central and eastern Saskatchewan, where morning lows could reach 0, though it would be a light frost. The low pressure system and associated front that produced the windy, cold weather Thursday will pull off to the east, and the sky will clear in central and western regions. Combining should be possible again in drier areas. In the afternoon, the western half of Saskatchewan should reach highs of 15 to 20 degrees, though it will remain cooler on the eastern side, with highs of 10 to 15.

Manitoba

Showers, mainly affecting western Canada, will taper off later in the day. There may be a slight risk of a light frost early Friday morning in western Manitoba, though the chances are greater in Saskatchewan. As the rain tapers off, the sky will slowly clear during the day, but it will remain cold. Below-average highs in the mid teens are expected. Harvest operations may be delayed, as fields remain wet from the recent rain.

Saturday and Sunday

Alberta

Both weekend days will be sunny and warm across Alberta, as the high pressure ridge aloft continues to build, reinforced by a developing ridge at the surface. The wind will come in from the south, and temperatures will climb to the mid 20s on Saturday, and to the mid to high 20s on Sunday.

Saskatchewan

Saturday morning, there will again be a risk of light, patchy frost, under a clear sky. This time, the risk will be greater in the eastern half of the province. Low all the way down to 2-4 degrees are likely, and some low-lying areas may drop to near zero. Sunday morning will be warmer, and a risk of frost is not anticipated. Afternoon highs on Saturday will reach the upper teens. On Sunday, it will be warmer with highs in the low 20s. Both weekend days will have good harvest weather.

Manitoba

Like Saskatchewan, there will be a risk of light, patchy frost on Saturday morning, and on Sunday morning, it will be warmer, with no risk. The sky will clear, and harvesting can resume as crops dry from the rain of recent days. Highs Saturday in Manitoba should reach the high teens, warming to the low 20s on Sunday. Harvest conditions will continue to improve quickly through the weekend.