Recent meteorological forecasts for Mexico City point to a daily high near 27°C on May 18, supported by ongoing seasonal warming in late spring and limited cloud cover that favors maximum solar heating. Current atmospheric conditions, including weak high-pressure influence and typical May subsidence, align with observed highs of 26–29°C over the preceding days and the month’s long-term average of 26–27°C at the Benito Juárez station. Ensemble model guidance shows only modest day-to-day variability, keeping the probability of 27°C or higher dominant while leaving room for slight cooling if unexpected moisture arrives from the south. Traders are incorporating these stable signals into the 80.5% implied odds for the top outcome.