The market's close spread across 27–29°C stems primarily from evolving forecast guidance for Chengdu's Sichuan Basin location on May 17, where official models from the China Meteorological Administration project a daytime maximum near the seasonal average of 26–28°C. Regional high-pressure patterns, combined with moderate solar insolation and variable cloud cover, support this range, while localized factors such as humidity from nearby river systems and downslope winds off the Tibetan Plateau introduce 1–2°C uncertainty that differentiates the leading outcomes. Traders closely track real-time station readings for resolution criteria, with any afternoon clearing or urban heat effects potentially pushing readings toward the upper end of current implied probabilities.