Forecasting the weather involves a lot of science, a little intuition, and, honestly, a touch of luck. This weekend may require more luck than usual. I'd typically look to weather events upstream of the overall flow pattern over central North America and figure out how things will evolve when they hit the Sault region. However, the features that will(might) hit the Sault region this weekend have yet to develop - making it more challenging.
I suspect that a cold front crosses the region early Saturday morning, then a warm front arrives in the evening, followed by a cold front Sunday morning and then possibly a Texas Low on Tuesday. Any or all of these features could change intensity and timing(or not develop at all!) to make a mess of the forecast. The best weather forecast this weekend might be the view from the kitchen window. If you are the gambling type, you could move all your chips onto my prediction below and spin the weather roulette wheel.
Friday morning brings a 30-40% chance of an isolated shower, and then cloudy skies linger for the middle of the day before partially clearing later in the afternoon. Temperatures climb back into the low 20s on a southerly breeze.
Scattered thunderstorms should move through the region early Saturday morning with cloudy skies for the rest of the day. Daytime highs should reach 20°C with a weak southerly wind. Scattered showers and storms move in sometime around sunset and linger overnight.
Sunday will bring a mix of sun and cloud with temperatures close to the 18°C mark. Periods of light rain are likely in the afternoon. Watch for a change in the weather pattern for next week as colder air returns to the region.