Recent forecast models from the Met Office and ECMWF indicate an overnight minimum temperature in London on May 20 most likely settling between 11°C and 13°C, driving the tight clustering of market-implied odds around those outcomes. This range reflects a mild southwesterly flow with moderate cloud cover that limits radiative cooling compared to clear-sky nights typical in mid-May, when historical averages hover near 9°C. Variable wind speeds and potential for patchy rain could further influence the exact low by altering heat retention at the surface. With resolution just three days away, traders are weighing the spread in ensemble guidance, where small shifts in timing or humidity could nudge the minimum by a degree in either direction.