Recent forecasts from the UK Met Office and European models point to overnight lows in London around 11–13°C on May 20, driven by persistent Atlantic low-pressure systems bringing cloud cover, light showers, and moderate southwesterly winds that limit radiative cooling. These conditions follow a cool, unsettled stretch through mid-May, with daytime maxima near 20°C but minimal temperature drops after sunset due to the insulating cloud layer. Historical May averages show lows near 9°C, yet current ensemble guidance places the most probable minimum slightly above that baseline. Traders appear focused on the narrow window between 10°C and 13°C as model runs converge on this range, with any late shift to clearer skies potentially allowing a dip toward single digits. Updated guidance expected within 48 hours could refine these probabilities ahead of resolution.