Current ensemble forecasts from the Met Office and ECMWF place London’s overnight minimum on May 18 near 7–9 °C, with the tight clustering of trader odds around those values reflecting model spread in boundary-layer cooling under variable cloud cover and light westerly flow. Scattered showers expected overnight will limit radiative heat loss, while modest wind speeds near the surface reduce the chance of sharper drops below 7 °C; conversely, any clearing could allow temperatures to settle closer to 9 °C. Historical May climatology shows average lows around 8 °C, so the current setup aligns closely with seasonal norms yet remains sensitive to the precise timing of frontal passages. Updated model runs and Met Office guidance issued over the next 24 hours will clarify whether the minimum settles at the lower or upper end of that narrow range.