The Met Office has extended its warning for ice "and small amounts of snow" to cover both Surrey and Hampshire.
A previous 'yellow' alert only covered Surrey, West and East Sussex, Greater London and Kent. But the warning area has now been extended to cover all of southern England.
It is valid between 3pm today (Monday) and 3am Tuesday morning.
The Met Office warning states: "Parts of southern Britain are likely to see some snow showers during Monday afternoon and the first part of the night.
"Most places will see little or no lying snow, but 1-2 cm may settle in one or two places, mostly over high ground.
"In addition, some icy surfaces are possible for a time. However, the chance this reduces by dawn on Tuesday as snow showers clear to the west and surfaces dry out."
Find out the latest information here.