Temperatures hit 18.3C on Monday as London basked in the warmest day of the year so far - beating the likes of Ibiza, southern Spain and the whole of France.
The temperature was recorded at Kew Gardens, west London, where visitors enjoyed temperatures 10 degrees warmer than Milan at 8C.
Northolt, north west London, also recorded 18.3C, which marks the warmest day of the winter so far. Heathrow Airport saw 18.1C.
Nicola Maxey, a Met Office spokeswoman, said the balmy temperatures were caused by tropical Atlantic air sweeping across the country.
She added that by the end of the week temperatures could be closer to single figures, with London expected to reach.