Warnings of snow and ice have been extended to many parts of the UK over the coming days.
Yellow weather warnings remain in place for parts of north-east Scotland and England until Wednesday morning.
The Met Office issued new updates on Monday which apply to much of the UK during the next five days.
Heavy snow could bring “significant disruption” to northern and central parts of the country on Thursday and Friday, it said.
A fresh warning of ice and some snow across areas of the Midlands, East, south of England and Wales comes into force between 21:00 GMT tonight and 10:00 on Tuesday.
This could lead to “difficult travel conditions” in some parts, the Met Office said.
Some roads and railways were likely to be affected in these areas, it said, and people should expect longer journey times.
A similar warning covering much of Northern Ireland is also in place over night.
Snow is likely to cause some travel disruption across parts of southern England and Wales throughout Wednesday, according to another warning.
Further warnings for heavy snow are in place for Thursday and Friday in much of Scotland, northern England, parts of the Midlands, north Wales and Northern Ireland.
Weather conditions may disrupt travel and other day-to-day activities.
The first Met Office warning began on Sunday evening for parts of Scotland covering places including Aberdeen and Dundee, the Highlands, Orkney and Shetland.
The warning in place on Monday encompasses more of Scotland and a corridor of north-east England that extends to Newcastle upon Tyne and Yorkshire.
For Tuesday, the warning area grows further to cover Strathclyde, more of Yorkshire and the Humber, and the East Midlands. Frequent snow is expected.
The Met Office said snow could cause delays on roads in these places, as well as rail and plane cancellations. It also warned of the risk of slips and falls on icy surfaces.
There was “slight chance” that rural communities could be cut off, it said, adding that cuts to power and phone services were possible.
BBC forecaster Sarah Keith-Lucas said Tuesday night could be the coldest of the week and one of the coldest of the year, with lows of -10C (14F) possible in Scotland.
She added that it was “not too unusual” to get these “cold wintry blasts” even after entering meteorological spring, due to the effects of air from the Arctic.
But the forecast for the middle of the week is less certain, with the arrival of warmer air from the Atlantic expected to create a “battleground” over the UK, she said.
She said this could bring snow to more southerly parts of England, or some much-needed rain following a dry six-week period.
Earlier alerts issued by the UK Health Security Agency also remain in place. These warn that all of England is likely to experience cold weather formuch of the week.
The agency said this could have a “serious impact” on the health of those who are vulnerable to cold weather, and urged people to check on relatives.
It advised over-65s, or those with pre-existing medical conditions, to heat their homes to at least 18C.