Recent National Weather Service and model consensus from the Global Forecast System and European Centre for Medium-Range Weather Forecasts indicate Chicago’s daily high on August 1 will likely fall in the low-to-mid 70s, with ensemble spreads reflecting modest uncertainty in afternoon mixing and boundary-layer moisture. Surface observations show dew points near 60°F and light winds under weak high pressure, limiting convective heating and keeping maximum temperatures below seasonal normals around 82°F. Traders assign nearly equal weight to the 70–71°F and 72–73°F bins because small differences in cloud cover or wind direction can shift the peak by 1–2°F. Later updates from the National Weather Service’s local forecast office and real-time mesonet data will refine these probabilities ahead of market resolution.