Latest Met Office guidance and ensemble models from the European Centre for Medium-Range Weather Forecasts point to a maximum of 25°C in London on June 17, driving the 33% market-implied probability for that outcome. A building high-pressure ridge and modest southerly flow support afternoon warming, yet variable cloud cover and potential showers introduce uncertainty that spreads implied odds across 24–26°C. These near-term forecasts align with post-heatwave normalization after May, where typical June maxima hover near 20–22°C but recent model runs have trended slightly warmer. Traders weigh resolution criteria tied to official observations at sites such as Heathrow, with updates from the next model cycles likely to refine the narrow range between leading probabilities.