Londoners will “feel the chill” over the next few days as the temperature is expected to hit zero overnight and see highs of 9C on Thursday.
The cold grip on the capital comes after a blitz of warm weather and more “spring-like” conditions over the past few weeks.
Met Office spokesman Richard Miles said Londoners “will definitely feel the chill over the next few days”.
He told the Standard: “It’s going to be much colder when compared with the recent warm weather.
“There is definitely a chance of early morning frost and even wintry showers and the northerly wind will make things feel even cooler.
“However, away from the South Downs, there is unlikely to be any snow settling and even there lying snow will be short-lived so there are no weather warnings currently in place.
“Temperatures will begin to warm again from the west of the UK into the weekend but the weather will remain unsettled and eastern areas including London will stay colder longer.”
Meanwhile, a yellow weather warning has been issued for parts of Scotland and the north-east of England from 8pm on Wednesday until 10am on Thursday.
Snow and hail showers could lead to icy surfaces, with possible travel disruption, the Met Office has warned.
Icy patches on some untreated roads, pavements and cycle paths, could lead to an increased chance of accidents or injuries while some travel disruption is expected.
Parts of the north and east will feel cold on Thursday with sunshine and blustery wintry showers forecast.
The dip in temperature is expected to continue over the weekend until Sunday.
Hopes of an April heatwave may be dashed for now.
Met Office forecaster Alex Burkill said: “It is normal to have colder weather in April but it’s far from the sunny, warm days seen last week.”
