A blast of Arctic air will bring freezing temperatures to the UK this week and end what has been a mild start to the new year.

Overnight frost and the possibility of rain showers turning snowy in some parts are forecast by the Met Office, though no weather warnings have been issued.

After a mild Monday and Tuesday, temperatures are expected to fall to freezing overnight from Wednesday for much of the country, and could plunge as low as -5C (23F) in rural areas of Scotland.

Bonnie Diamond, a meteorologist, said the cold polar air from the north-west will switch to a colder Arctic airflow from the north.

“Through Wednesday a polar maritime air mass is going to push in from the west, but by the time we get to Thursday it will be an Arctic air mass,” she said.

North-east Scotland had some snowfall on Monday, and expected rain showers could turn to snow by Friday in western parts of the UK, Diamond said.

The Met Office forecast the weather will be windy on Wednesday with rain moving south-eastwards. It is then predicted to get colder but brighter, with widespread frost and wintry showers in the north-east.

Friday could bring thickening cloud and outbreaks of rain, which is expected to move eastwards on Saturday. It is expected to remain mainly cold, unsettled and sometimes windy thereafter, according to the Met Office.

Average daytime temperatures in the south of England will struggle to rise above 6C. While this is the average temperature for January, Diamond said the sharp change from the mild weather will be noticeable across the country.

“Other than the odd cold snap for some parts for the first half of January, it has been relatively mild, but this week is a transition to colder weather for the entire country and will be noticeable for all of us, and we’re going to really feel the switch to colder temperatures,” she said.

The Met Office said that while temperatures are expected to drop, bringing an enhanced risk of snow and widespread frost across the UK, this does not mean the return of the so-called Beast from the East, which brought heavy snowfall last year.

Diamond said: “Just because the wind is coming from the east does not necessarily mean we are going to see a repeat of last year.”