Trader consensus on Polymarket has priced "26°C or higher" at a near-certain 100% implied probability for Mexico City's highest temperature today, April 18, driven by updated hourly forecasts from major meteorological services like AccuWeather and The Weather Channel projecting daytime peaks of 28–31°C (82–88°F) under dominant high-pressure conditions and abundant sunshine. Current observations show morning temperatures already climbing from 15°C (59°F) toward afternoon maxima, consistent with model ensembles reflecting minimal cloud cover and dry-season stability at Mexico City's 2,240-meter elevation. This positioning aligns with April climatology, where highs average 25–27°C but synoptic patterns often push above 26°C. Realistic challenges include an unexpected mid-afternoon cold front or thick stratus clouds suppressing solar heating, though low-probability given 24-hour forecast stability; final resolution awaits official airport station data by evening.