Recent high-pressure dominance across central Mexico has sustained clear skies and strong daytime insolation at Mexico City’s 2,240 m elevation, driving observed highs of 26–29 °C on May 14–15 and positioning the May 18 maximum near or above the 27 °C threshold. Servicio Meteorológico Nacional forecasts and model consensus project 27–28 °C under mostly sunny conditions, consistent with the 88.5 % market-implied probability for 27 °C or higher. Although the rainy season is beginning, widespread cloud cover or measurable precipitation remains unlikely on the 18th, limiting cooling potential. Historical May climatology at Benito Juárez airport averages 26 °C, so current conditions represent a modest positive anomaly; final hourly observations will resolve the market within 48 hours.