**Trader sentiment for the lowest temperature in London on August 23 centers on model consensus for a mild overnight minimum around 13–14 °C, driven by high pressure maintaining clear or partly cloudy skies that permit moderate radiative cooling without extreme drops.** Official guidance from the Met Office and BBC forecasts a daytime high near 23–24 °C and nighttime low of 13–14 °C under sunny intervals and light winds, consistent with the market’s heaviest weighting on those two outcomes. Recent shifts from an earlier hot spell have introduced slightly cooler, more stable Atlantic air, reducing the likelihood of sub-12 °C readings while limiting further warming that could push the minimum above 15 °C. Key differentiating factors include the degree of overnight cloud cover (which traps heat and raises the floor) versus clear skies enhancing long-wave radiation loss, plus urban heat-island effects and light wind speeds that modulate cooling rates. Ensemble spreads in short-range models remain narrow this close to the event, explaining why 13 °C and 14 °C probabilities sit so close together; any late adjustment in cloud timing or a marginal frontal approach could tip the balance within the narrow 11–15 °C range still carrying meaningful probability.