London is plunging into a week-long cold snap with temperatures expected to feel as chilly as -2C even during the day - while a severe cold weather alert kicks in for millions across the UK.
Temperatures in the early hours of Thursday were expected to drop to at least freezing in the capital, with lows of -2C predicted for the following night.
Day time temperatures are expected to stay at freezing or scarcely above for several days, with temperatures feeling as low as -4C by 9am on Saturday, according to the Met Office.
The freezing conditions has caused Mayor Sadiq Khan to activate emergency cold weather measures amid fears it could pose a risk to life. Councils and charities across London are being asked to provide extra beds for those sleeping rough.
Meanwhile, a level 3 cold weather warning issued by the UK Health Security Agency began on Wednesday evening. Covering the whole of England, it currently runs until Monday, December 12.
The alert means those with certain vulnerabilities are being advised to maintain indoor heating temperatures of at least 18C to ward off the cold.
In its forecast for Thursday for the capital and the South East, the Met Office said: “A very cold day with temperatures struggling to rise much above freezing for many.
“Dry with often long sunny spells for most, although some patchy cloud likely through the morning. Maximum temperature 3 °C.”
Outside of London, yellow weather warnings of snow or ice were also in place for parts of Scotland, Wales, Northern Ireland and the east coast of England and the south-west.
Met Office meteorologists said there was some uncertainty around how long the cold spell, branded the Troll from Trondheim, will last.
However, it is expected to stay cold into next week with temperatures remaining well below average for the time of year.
Met Office Chief Meteorologist Steve Willington said: “As an Arctic maritime airmass settles across the UK temperatures will fall with widespread overnight frosts, severe in places, and daytime temperatures only a few degrees above freezing.
“However, the cold air from the Arctic will also bring brighter conditions, with some dry, sunny spells, particularly away from the coast and where winds are light it could feel pleasant in the sunshine. Some patchy freezing fog is also likely. ”
Health officials have warned that the impact of the cold could be particularly problematic for older people and those with certain health conditions.
Dr Raquel Nunes, of Warwick Medical School, said it meant an “increased probability of respiratory and cardiovascular diseases, falls and injuries, as well as hypothermia with older people, those chronically ill, children and homeless”.
