Current ensemble forecasts from the Met Office and European Centre for Medium-Range Weather Forecasts place London's minimum temperature on May 19 in the 10–12 °C range, with the tight clustering of market-implied odds around these values reflecting modest but genuine uncertainty in overnight radiative cooling. Persistent Atlantic low pressure is expected to deliver moderate cloud cover and south-westerly winds that limit clear-sky heat loss, while daytime maxima near 17 °C provide limited daytime heat storage. Historical May minima in central London average 8–9 °C, so the present guidance sits slightly above climatology; however, small shifts in cloud timing or wind speed over the next 48 hours could easily push the recorded low toward 9 °C or 13 °C. Updated model runs tonight and tomorrow morning will be the key data releases likely to refine trader positioning.