Official forecasts from the National Weather Service indicate a strong cold front will deliver well-below-normal temperatures to Denver on May 18, with daytime highs projected in the mid-40s Fahrenheit amid widespread cloud cover and light precipitation. This positions the market overwhelmingly toward 61°F or below because seasonal averages for mid-May hover near 75°F, and current model consensus shows no rapid warming trend through the period. Historical analogs from similar late-spring cold outbreaks confirm such drops are common when Arctic air intrudes behind a Pacific storm system. The primary uncertainty remains whether a last-minute shift in the jet stream could allow brief clearing and slight warming before peak heating, though forecasters assign low probability to any outcome above the low-60s range.