Interestingly, even though there was not a lot of confidence in much of last week’s forecast, it was the lower-confidence second half of the forecast that ended up being the most accurate. This means it looks like we are in for a period of cool weather after nearly three months of above-average conditions.
Looking at the big picture, a large and deep trough of low pressure is taking shape over Hudson Bay and northeastern Canada. This will bring cool and unsettled conditions to this region. To the west, a ridge of high pressure is building, meaning dry and warm weather for those regions. Our regions will be stuck in the middle, which means we will probably end up being impacted by both.
For most of this forecast period it looks like we’ll be under the influence of the cold eastern trough of low pressure. This means we should expect partly to mostly cloudy skies with chances of showers almost every day. The flow around the eastern low and the western high will place us under a strong northwesterly flow, resulting in windy conditions. Disturbances rotating around the trough of low pressure will bring good chances of showers every couple of days, but the exact timing of these systems is difficult due to the strong flow.
Temperatures will start off seasonable but will quickly cool down as the northwesterly flow establishes itself. Expect daytime highs to be around 20 C on Sept. 2, slowly cooling down into the mid-teens by Sept. 8. Overnight lows will greatly depend on cloud cover. On cloudy nights temperatures should only drop to around the 10 C mark. If it clears up expect much cooler temperatures. In fact, the weather models are showing temperatures dropping to near the freezing mark early next week.
Looking further ahead, the weather models show the western ridge pushing eastward during the second half of next week, bringing with it plenty of sunshine and a return to warm temperatures.
Usual temperature range for this period: Highs, 17 to 26 C; lows, 5 to 13 C.