**Extremely dry conditions have defined August 2026 in London so far, with only about 3 mm of precipitation recorded through late August against a long-term average near 52 mm.** This places the month on track for one of the driest on record until an unsettled pattern arrived in the final week. Low pressure moving in from the southwest is now driving thundery showers and heavier downpours, with forecasters expecting multiple days of rain and thunderstorms through the bank holiday weekend. These late-month developments create the primary uncertainty separating the closely matched leading buckets (<30 mm and 30-40 mm). Model guidance and historical analogs suggest the remaining days could add 10-30 mm depending on shower intensity, duration, and exact tracks, keeping totals well below normal but potentially pushing into the low 30s. Higher buckets remain less favored given the short window and variable convective nature of the rain. Market-implied odds reflect traders weighing these forecast uncertainties against the very low baseline accumulated to date.