Temperatures as we roll through the weekend will run about 10° - 15° above normal, which as of September 26th is a mild 69 degrees. That puts us into the 70s and 80s for the weekend, but next week, temperatures will be running 10° - 20° below normal. By Tuesday, temperatures will only be in the upper 50s with temperatures Friday of next week, only near 50 degrees.
What is driving this wild week of weather? For the weekend, we will be under a ridge of high pressure, leading to sinking dry air. That promotes plenty of sunshine and with a southerly breeze, temperatures will fly well into the 70s and 80s. That ridge will move out starting Sunday and a trough of cold air straight from Canada will replace it.
The Canadian air will be downright chilly. That combined with the warm Lake Michigan waters will lead to lake-effect rain showers and the return of the permacloud. Sunshine will be a rarity next week and the cold air will only strengthen as it hangs overhead. The cloudier skies will keep frost at bay if there is any good news out of this.
If you are going to enjoy the last summer weekend of the year by going out to Lake Michigan, make sure you are staying out of the water and off of the piers! Strong south to southwest winds around 15 to 30 mph will kick up waves to 8 feet by the evening. Water will rush over the piers as a result leading to the risk that you could be swept out into the lake. The rip current risk will also be high! This continues into our Sunday as well.