Traders see 26°C and 27°C as nearly even favorites for Mexico City’s peak temperature on August 15 because short-range numerical weather prediction models show the city hovering near that narrow threshold amid typical late-summer variability. At 2,240 meters elevation, diurnal heating is moderated by the surrounding mountains and frequent afternoon cloud build-up from the North American monsoon, keeping maximums close to long-term August averages of 24–26 °C. Urban heat-island effects and slight differences in boundary-layer moisture or wind speed can easily shift the observed high by one degree, while ensemble spreads from agencies such as the Servicio Meteorológico Nacional still encompass both values. Updated model runs and official 24-hour forecasts expected later today will likely tighten or shift these probabilities before the market resolves.