Recent National Weather Service model runs show Miami under a subtropical ridge with light easterly flow, producing afternoon highs most likely in the mid-to-upper 80s on May 19. The near-even split between the 86–87 °F and 88–89 °F brackets stems from small differences in predicted cloud cover and the timing of the sea-breeze front, both of which can cap daytime heating by 1–2 °F. Historical May climatology at Miami International Airport places the normal maximum at 87 °F, with recent days running slightly above average after an early-month heat surge. Updated guidance from the 12Z and 18Z model cycles, plus any overnight convective outflow, will be the decisive inputs before the market resolves.