Recent atmospheric patterns over the North Atlantic are driving substantial uncertainty in minimum temperatures for London on May 25, with ensemble forecasts from the Met Office and ECMWF showing divergence between cooler northerly flows and warmer southerly intrusions. Current model runs indicate a potential high-pressure buildup that could suppress cloud cover and allow overnight radiative cooling to dip below 10 °C, while competing scenarios favor milder maritime air yielding lows near or above 15 °C. Historical May climatology places average overnight minima around 8–10 °C, yet recent sea-surface temperature anomalies in the eastern Atlantic are tilting probabilities toward slightly elevated values. Traders are weighting the wide spread between sub-10 °C and 20 °C+ outcomes because the four-day forecast horizon still permits significant shifts from incoming pressure gradients or frontal passages.