Forecast models from Environment Canada and major ensembles show high uncertainty for Toronto's July 31 maximum, with consensus clustering near 28–30°C amid variable high pressure, modest humidity, and light winds. Recent runs highlight small differences in timing of any weak frontal passage or afternoon cloud build-up that could cap or boost readings by 1–2°C, keeping 29°C and 30°C as the closest market outcomes. Historical July climatology places typical highs around 27–28°C, but this year's warmer baseline and limited model spread explain why probabilities remain distributed across the 28–31°C range rather than converging on a single value. Updated guidance expected overnight will likely refine the envelope ahead of market resolution.