**Mild late-summer conditions centered on 21–22°C are driving the tight market split between those two outcomes.** Official Met Office guidance for 22 August forecasts sunny intervals with a daytime maximum of 21°C, consistent with long-term August averages near 22°C and the absence of strong high pressure or southerly flow that would support higher readings. Ensemble model output from the Met Office and ECMWF places the most likely peak in the 20–23°C window, with the spread reflecting typical uncertainty in maximum temperature timing and local effects such as cloud cover or wind direction. Recent model runs have remained stable without sharp warming signals, keeping extreme tails (25°C+) at negligible implied odds while making 21°C and 22°C the clearest focal points for resolution. Traders are weighting the official forecast and ensemble consensus, which favor these two values over cooler or warmer alternatives given current steering patterns and limited diurnal heating potential.