Forecast models from the National Weather Service and private sources converge on overnight lows in the upper 60s to low 70s for Atlanta on September 17 under clear skies and light, variable winds associated with high pressure. Radiational cooling will drive the minimum, yet elevated dew points near 60–65°F and a recent stretch of highs in the low 90s limit how far temperatures can fall. Slight differences in model timing and boundary-layer mixing explain the tight clustering of market-implied odds around 66–71°F bins. No significant frontal passage or moisture surge is expected before dawn, keeping the outcome range narrow relative to climatological variability. Updated model runs and official NWS briefings on the 16th will provide the next key data points for resolution.