Official Met Office observations confirm London's lowest temperature on April 28 reached exactly 9°C, primarily at Heathrow Airport's weather station—the standard reference for such metrics—with other central sites like St. James's Park recording similar minima. This outcome aligns with pre-event forecast consensus from UKMO and ECMWF models predicting mild overnight lows of 8–10°C under clear skies, light winds, and no significant cold air advection or radiative cooling inversions that could have driven sub-8°C readings. Trader sentiment reflects this verified data, with 100% implied probability on 9°C as the market nears resolution. Realistic challenges would require rare data revisions from station audits or discrepancies in multi-site validations, though historical precedent shows such adjustments affect less than 1% of daily records. Next hourly bulletins from the Met Office could provide final verification.