Those celebrating the arrival of the new year will have to brave cold temperatures, with an amber health alert in place across parts of the UK.
Forecasters warned the end of 2025 will not be "particularly fantastic", with temperatures around 7-8C, but things will take a turn for the worse as 2026 arrives.
The next few days will be cold and cloudy overall, according to Sky News meteorologist Dr Christopher England, although there will be clearer spells, bringing a threat of overnight frost and fog.
It will be breezy in the south, Dr England added, while the north should expect some hard frosts.
Find out the forecast for your area
Northern areas are expected to be subjected to the worst of the chillier conditions from New Year's Day onwards.
Met Office forecaster Dan Stroud said: "We're losing this sort of settled but chilly conditions, and bringing in something a little bit more showery with more wintry hazards in the forecast, particularly for the north of the country."
Amber cold health alert issued
The UK Health Security Agency (UKHSA) has issued an amber cold health alert for the North East and North West of England - where temperatures are expected to fall to around 3-5C - from 8pm on Sunday to 12pm on 5 January.
The agency said the weather is "likely" to cause significant impacts across health and social care settings, including a "rise in deaths" among those with health conditions or aged 65 or over.
It added that the UK may also see "impacts on younger people" and said there will likely be an "increase in demand for health services" across the regions.
Impact from cold temperatures
Other impacts include "temperatures inside places like hospitals and care homes dropping below the levels recommended for assessing health risks" and "challenges keeping indoor temperatures at the recommended 18C leading to more risk to vulnerable people", the UKHSA said.
It also warned of staffing issues due to external factors such as travel delays, and said other sectors such as transport and energy could start to see the impacts.
The agency also issued a yellow cold health alert for the East Midlands, West Midlands, South East, South West, East of England, Yorkshire and the Humber, and London.
Temperatures are expected to fall to around 4-6C from New Year's Day in areas covered by the yellow health alert.
Warning of 'serious' health impact
Dr Agostinho Sousa, head of extreme events and health protection at UKHSA, said: "As the colder weather sets in it is vital to check in on friends, family and neighbours that are most vulnerable.
"The forecasted temperatures can have a serious impact on the health of some people, leading to increased risk of heart attacks, strokes and chest infections, particularly for individuals over the age of 65 and those with pre-existing health conditions."
It comes after a state of emergency was declared in New York as a powerful winter storm disrupted one of the busiest travel weekends of the year.
(c) Sky News 2025: Cold temperatures forecast for new year, with health alerts issued
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