Recent National Weather Service model runs have introduced significant uncertainty into Miami’s minimum temperature outlook for May 21, with ensemble guidance showing a broad spread driven by variable steering flow and the potential for either cooler northerly advection or persistent subtropical high pressure. This forecast divergence explains the nearly even market-implied odds between sub-74 °F outcomes and those exceeding 90 °F, as traders weigh the strength of any approaching frontal boundary against typical May climatology where overnight lows average near 73 °F. Upcoming updates from NOAA’s Global Forecast System and local Miami offices will likely narrow the range as the date nears.