**Current forecasts position mid-70s as the most likely range for Chicago’s highest temperature on June 15, 2026.** Official guidance and ensemble model consensus from the National Weather Service indicate a high near 73–76 °F under northwest flow behind a departing frontal system, with partly to mostly sunny skies and light winds limiting daytime heating. This places the outcome well below the 1991–2020 normal high of 80.5 °F for the date and explains why 76–77 °F (38 %) and 74–75 °F (27 %) dominate trader pricing. Key drivers include the timing of the frontal passage, which has already introduced cooler, drier air, and the absence of strong southerly return flow or building high pressure that would support greater warming. Ensemble spreads remain modest, with limited upside risk from diurnal mixing or localized clearing; downside risk is similarly constrained by mostly clear conditions expected overnight into the morning. Resolution will hinge on the official high recorded at Chicago Midway (KMDW) per National Weather Service climatological reports, with any last-minute model shifts in boundary-layer moisture or wind direction the primary variables that could nudge the outcome toward the adjacent 78–79 °F or 72–73 °F bins.