Exceptionally dry conditions at London Heathrow—official measurement site for this market—have positioned the <20 mm outcome at 78.5% implied probability, with just 3 mm recorded through April 16 against a 42 mm monthly normal from the Met Office. Following a saturated winter, persistent high pressure over southeast England has suppressed Atlantic moisture, yielding mostly trace precipitation (e.g., 2.4 mm max on April 12) and above-normal temperatures (monthly mean 11.6°C vs. 10.5°C normal). Current Met Office forecast models indicate limited rainfall potential for the remaining two weeks, though shifts in steering patterns could introduce showers; traders await daily updates and end-month totals for resolution.