In a statement issued just minutes ago Mr Drakeford said: "Today, I met the First Ministers of Scotland and Northern Ireland, and Michael Gove, from the UK Government, to discuss the very latest information on a new strain of coronavirus.
"We now know that this new strain is significantly more infectious and spreads more quickly than the original one.
"Many of you will have heard the Prime Minister this afternoon setting out the pattern of transmission in London and the South East of England, which has been linked to this new variant of coronavirus.
"This is remarkably consistent with the rapid acceleration of transmission in Wales and the high rates of cases we have seen in recent weeks.
"The latest evidence suggests this new strain is present throughout Wales.
"Throughout the public health emergency, we have had to respond quickly to the rapid changes, which have been so typical of coronavirus.
"Today has been one of those days when new information has required an immediate response.
"This afternoon, the Cabinet met to discuss this worrying new development in the pandemic and to hear the latest advice from our senior medical and scientific advisers, including the impact on our NHS.
"The situation is incredibly serious. I cannot overstate this.
"We have therefore reached the difficult decision to bring forward the alert level four restrictions for Wales, in line with the action being taken in London and the South East of England.
"These new restrictions will come into effect from midnight tonight instead of during the Christmas period."
He added: "This will mean non-essential retail, close contact services, gyms and leisure centres and hospitality will close at the end of trading today.
"Stay-at-home restrictions will also come into effect from midnight.
"Unfortunately, we must also look again at the arrangements for Christmas – we cannot expose people to the risk of this new, more virulent strain of coronavirus.
"We will therefore change the current rules, which allow two households to come together to form a Christmas bubble over a five-day period, so that they will apply on Christmas Day only.
"Throughout the alert level four period, a single person household will be able to join with one other household.
"While we all want to avoid further disruption to businesses and plans for Christmas, our overriding duty is to protect lives here in Wales.
"We know that 2021 will be a different and a better year.
"Our economy will recover.
"Christmas will come again.
"But lives which are lost, are lost for ever.
"This new strain of the virus is another dreadful surprise in this long-running pandemic.
"We now have a pandemic within a pandemic, a crisis within a crisis.
"It is another challenge we must overcome. But one we will overcome together.
"We will continue to protect ourselves and our loved ones, and, together, we will keep Wales safe."