Current forecast models indicate an overnight minimum near 15–16°C for Toronto on August 21, driving the tight clustering of market-implied odds around 12–16°C. Clear to mostly clear skies under a high-pressure ridge promote strong radiative cooling after sunset, aided by light northerly to easterly winds of 2–6 mph that limit mixing and allow surface temperatures to drop toward dew points near 11–13°C. This setup aligns with GFS guidance showing early-morning readings around 15°C, below the 17.3°C climatological average low. Uncertainty in the precise minimum arises from observation timing, urban heat island effects, and minor model spread, keeping probabilities distributed across the 12–16°C outcomes rather than concentrating on a single value.