**Recent forecasts from multiple models and agencies, including ECMWF runs and local services like the Servicio Meteorológico Nacional, point to a high temperature in Buenos Aires on September 23, 2026, most likely between 16°C and 20°C, with the strongest consensus around 18–19°C.** This aligns closely with market-implied probabilities favoring 19°C (42.5%), 20°C (25.5%), and 18°C (23%). September 23 falls during the Southern Hemisphere spring transition. A cool, windy period with southwesterly flow dominated the prior days (highs near 13–14°C on September 22), but a shift to northerly winds is expected to advect milder air northward. This setup typically produces gradual daytime warming under partly to mostly cloudy skies, with limited moisture and low precipitation chances keeping temperatures from spiking higher or dropping sharply. Model outputs show highs clustered near 16–18°C (some ECMWF and Yr.no guidance) to 18–20°C (tutiempo, Meteocity, and Argentine media summaries), reflecting typical spring variability around the long-term September 23 average of roughly 17–18°C. Key variables influencing the exact peak include the strength and timing of the northerly flow, afternoon cloud cover reducing insolation, and any minor model spread in boundary-layer mixing. The market’s heavy weighting toward 18–20°C reflects this narrow forecast envelope and the low likelihood of outliers below 16°C or above 21°C given current steering patterns and seasonal baselines. Updated model runs and official briefings on the 23rd itself will provide the final resolution data.