The whole of England has been hit with an amber "Cold Health Alert" by the UK Health Security Agency - which has warned that upcoming weather could lead to a "rise in deaths".
The authority has issued the alert across the country until Tuesday at 9am as "forecast weather is likely to cause significant impacts across health and social care services" as the mercury plummets.
The UKHSA warns that falling temperatures will take a particular toll on over-65s, and adds that "we may also see impacts on younger age groups".
Meanwhile, temperatures inside hospitals, care homes, and clinics could drop below the levels recommended for assessing health risks, the body added.
Temperatures are set to fall to as low as 0C in parts of southern England over the coming day.
More broadly, things are warmer further north - with parts of Scotland and Wales reaching 10C as the amber alert comes to a close.
The Met Office's five-day forecast says that conditions will "stay largely cloudy across the north with light outbreaks of rain and drizzle", while it will be "dry and cold in the south with some clear spells, allowing for patchy fog and frost".
Heading into Tuesday, forecasters say the day will be "largely cloudy and dry for most, although outbreaks of drizzle will continue across western hills".
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"Some brighter spells are possible in southern England and eastern Scotland. Mild for many," the Met Office adds.
Despite weather forecasts looking brighter over the coming days, the south of the country is still bracing for a string of flood alerts.
A total of 25 warnings have been put out across southern areas - but while local flooding is possible, it's not expected, the Environment Agency says.
"Land, roads and some properties may flood and there may be travel disruption", a notice reads.
Looking further forward, the Met Office's long-range forecast for Friday and beyond says: "High pressure will lie close to the southeast of the UK initially, with generally settled conditions across many parts.
"Cloud amounts will be variable, with some frost and fog in the south and east. This will be slow to clear, but some rain in the far northwest.
"Temperatures are likely to be generally a little above average, especially in the north, though more frost and fog patches are likely under clearer skies and lighter winds."
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The authority has issued the alert across the country until Tuesday at 9am as "forecast weather is likely to cause significant impacts across health and social care services" as the mercury plummets.
The UKHSA warns that falling temperatures will take a particular toll on over-65s, and adds that "we may also see impacts on younger age groups".
Meanwhile, temperatures inside hospitals, care homes, and clinics could drop below the levels recommended for assessing health risks, the body added.
Temperatures are set to fall to as low as 0C in parts of southern England over the coming day.
More broadly, things are warmer further north - with parts of Scotland and Wales reaching 10C as the amber alert comes to a close.
The Met Office's five-day forecast says that conditions will "stay largely cloudy across the north with light outbreaks of rain and drizzle", while it will be "dry and cold in the south with some clear spells, allowing for patchy fog and frost".
Heading into Tuesday, forecasters say the day will be "largely cloudy and dry for most, although outbreaks of drizzle will continue across western hills".
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"Some brighter spells are possible in southern England and eastern Scotland. Mild for many," the Met Office adds.
Despite weather forecasts looking brighter over the coming days, the south of the country is still bracing for a string of flood alerts.
A total of 25 warnings have been put out across southern areas - but while local flooding is possible, it's not expected, the Environment Agency says.
"Land, roads and some properties may flood and there may be travel disruption", a notice reads.
Looking further forward, the Met Office's long-range forecast for Friday and beyond says: "High pressure will lie close to the southeast of the UK initially, with generally settled conditions across many parts.
"Cloud amounts will be variable, with some frost and fog in the south and east. This will be slow to clear, but some rain in the far northwest.
"Temperatures are likely to be generally a little above average, especially in the north, though more frost and fog patches are likely under clearer skies and lighter winds."
Find Out More...