**Official forecasts from the National Weather Service Miami office and supporting models indicate a high in the upper 80s for Miami on September 22, 2026, with afternoon thunderstorms likely to develop after peak heating.** Persistent moisture, an upper-level low remnant, and south-to-southeast flow maintain humid conditions and elevated rain chances (around 70%), allowing temperatures to climb into the mid-to-upper 80s early in the afternoon before convective cooling and cloud cover set in. This produces the tight clustering around 86–89°F in trader pricing. The near-even split between 86–87°F and 88–89°F reflects uncertainty in thunderstorm timing and coverage: earlier or stronger convection could cap the daily maximum closer to 86–87°F, while delayed or less widespread storms permit a brief spike toward 88–89°F. Historical September norms in Miami feature daytime highs near 88–90°F under similar patterns, but the current wet regime slightly suppresses peaks relative to drier analogs. Updated model runs and NWS briefings through the morning of the 22nd remain the key near-term catalysts for any final shift in implied probabilities.