Mr Morgan said: "We've basically got this battleground taking place over this weekend between cold air across Scandinavia and Central Europe, which is affecting eastern parts of the UK, but towards the west is a little bit milder.
However, some areas could go 10 days without any sunshine, which is "near record-breaking", Met Office meteorologist Tom Morgan said.
"The Atlantic is trying to shift that cold air out of the way, pushing from west to east across the UK, but it's a very slow process and it will take until the middle of the coming week for conditions to turn much milder nationwide.
The Met Office said people could see sunshine return as soon as Monday in some parts of the country.
An anticylonic gloom happens when "high pressure traps a layer of moisture near to the Earth's surface", Met Office spokesman Stephen Dixon explains.
