Latest National Weather Service guidance and ensemble model consensus point to a daytime high near 79°F in Chicago on May 18, driven by southerly flow ahead of an approaching warm front that will push readings several degrees above the climatological normal of 71°F. This setup, reinforced by stable steering patterns and a slight severe-weather risk noted by the Storm Prediction Center, underpins traders’ strong preference for the 78°F-or-higher bin. Any cooler outcome would require an unexpected cold-air surge or major model shift, both low-probability scenarios given the short forecast horizon. Updated short-range runs and official briefings over the next 24 hours will further refine the exact maximum before resolution.