Trader sentiment for Miami's minimum temperature on May 21 centers on substantial uncertainty in numerical weather models amid a transitional late-spring pattern. With market-implied odds nearly even between outcomes at or below 73°F and at or above 92°F, the primary drivers are steering currents from the Gulf of Mexico and potential intrusions of drier continental air versus persistent subtropical ridging. Historical May climatology places typical overnight lows near 75°F at Miami International Airport, but current ensemble forecasts show divergence in low-level moisture and boundary-layer mixing that could shift readings by 15–20°F. National Weather Service model updates over the next several days will likely clarify these variables ahead of the official 24-hour minimum observation used for resolution.