Forecasters at the Met Office are warning of an “extreme weather event” hitting southern England this evening and overnight.

The Met Office updated its website for London and South East England with the severe weather warning at 11.35am.

Residents in Oxfordshire, Hampshire, West Berkshire and Southampton have all been warned to expect a heavy snowfall.

The warning says: “A period of exceptionally heavy snowfall is expected, with accumulations of 15-30cm, and perhaps in excess of 40cm.

“This is expected to cause widespread disruption to the transport network and could lead to problems with power supplies.

“The public is advised to take extreme care and refer to the Highways Agency for further advice on traffic disruption on motorways and trunk roads.”

This morning the Met Office was predicting a possible snowfall for the region of up to 20cm.