Trader consensus on Polymarket heavily favors under 20mm total precipitation for London in April 2026 at 65% implied probability, driven by an exceptionally dry start to the month amid a persistent high-pressure ridge over southern England. Met Office observations confirm negligible rainfall at Heathrow—London's reference station—through mid-April, following below-average totals in March for central and southern regions and a prolonged dry spell from late February. Early April delivered record warmth, peaking at 26.5°C in Kew Gardens on April 8, with minimal showers under sunny anticyclonic conditions. Updated Met Office forecasts point to cooler, unsettled patterns with scattered showers through month-end, but ensemble models suggest below-climatological-average accumulation (historical April mean ~42mm), though inherent forecast uncertainty remains from shifting Atlantic lows. Next advisories expected daily.