Recent forecast model runs from Environment Canada and the Global Forecast System reveal high uncertainty for Toronto's peak temperature on August 29, driven by the position of a slow-moving frontal boundary and variable warm-air advection over the Great Lakes region. Southern Ontario's lake-moderated climate can produce sharp day-to-day swings, with Lake Ontario breezes either suppressing or enhancing surface heating depending on wind direction. Traders see near-even odds for extremes because ensemble guidance splits between a warmer scenario exceeding 32°C under prolonged southerly flow and a cooler one dipping to 22°C or below if a cold front advances faster than projected. Historical late-August variability, with typical highs near 25–27°C, underscores why mid-range outcomes cluster around 25% while the tails reflect model divergence expected to resolve with updated 00Z and 12Z runs.