Trader sentiment for Shanghai’s June 18 maximum temperature centers on the ongoing Meiyu (plum rain) season, which brings persistent cloud cover, high humidity, and scattered showers that limit daytime heating and keep readings clustered near the climatological average of 27–29 °C. Latest official guidance from the China Meteorological Administration and regional models shows a narrow envelope of 27–31 °C, with the 28 °C outcome favored because widespread stratus and light easterly flow are expected to cap insolation. Minor differences among the leading bins reflect uncertainty in exact precipitation timing and boundary-layer mixing; stronger afternoon clearing or a brief sun break could push the peak to 29–30 °C, while heavier or earlier rain would favor 27 °C or below. Official station data at the end of the calendar day will resolve the market.