The Met Office has issued a severe weather warning ahead of a sudden cold snap tonight.
The yellow category warning will be in place from 10pm tonight (Wednesday) until 11am tomorrow (Thursday) across Dacroum with Hemel Hempstead, Berkhamsted and Tring under threat as is much of the south east.
Forecasters are warning of ice patches developing with wintry showers as temperatures plummet following a mild few days.
People are being warned to take care on pavements and roads, many of which could be untreated.
Weather warnings for snow and ice have been issued for much of the UK.