The Met Office has issued a severe weather warning and says that extremely cold conditions, with the possibility of more snow, will endure in Letchworth and surrounding areas until Sunday.

This is an update to a current cold weather alert and extends the existing Level 3 Alert until Sunday morning (December 18).

The Met Office says weather will be very cold at first with severe overnight frosts in places, especially over snow cover. 

A rapid transition to milder conditions is expected through Sunday. During the transition to milder air on Sunday a band of snow is expected across England, perhaps heavy at times, but readily turning to rain as the milder air feeds in from the southwest. 

There remains a degree of uncertainty regarding the extent of this snow. It should be noted that this may be a relatively short milder interlude with cold weather expected to return from the north next week.

The Met Office adds: "Look out for friends and family who may be vulnerable to the cold, and ensure they have access to warm food and drinks and are managing to heat their homes adequately.

"Try to maintain indoor temperatures to at least 18°C, particularly if you are not mobile, have a long-term illness or are 65 or over. 

"Avoid exposing yourself to cold or icy outdoor conditions if you are at a higher risk of cold-related illness or falls."