Under the category, also known as tier two, household mixing will be banned indoors with the rule of six in operation outdoors and in private gardens.
And while hospitality businesses will not be forced to close, friends and family who do not live together will not be able to mix at them.
Boris Johnson said in the Commons today that the months ahead will “test the mettle” of the United Kingdom.
He told MPs: “Though I must warn the House again that the weeks and months ahead will continue to be difficult and will test the mettle of this country, I have no doubt at all that together we will succeed.”
Both South and West Yorkshire will fall under the “high” alert level, according to MPs who spoke to the Health Secretary this afternoon, while North Yorkshire, and Hull and the East Riding will remain under the “medium” tier, according to a document released by No 10.
Setting out the new system, Mr Johnson said areas listed as medium will be subject to the same rules as those which currently apply across the country, such as the rule of six and the 10pm hospitality curfew.
In the high alert level, which will apply to most of the areas already subject to restrictions, household mixing will be banned indoors. Support bubbles will still be permitted, however.
The very high alert level will apply to areas causing the most concern, and social mixing will be prohibited indoors and in private gardens.
Pubs and bars will be closed in the very high alert level areas unless they can operate as a restaurant. People will also be advised against travel in and out of the areas.
Mr Johnson said: “We will now simplify and standardise our local rules, by introducing a three tiered system of local covid alert levels in England set at medium, high and very high.
“The medium alert level will cover most of the country and will consist of the current national measures, this includes the rule of six and the closure of hospitality at 10pm.
“The high alert level reflects the interventions in many local areas at the moment.
“This primarily aims to reduce household to household transmission by preventing all mixing between different households or support bubbles indoors. In these areas the rule of six will continue to apply outdoors where it is harder for the virus to spread in public spaces as well as private gardens.”
He said: “Most areas which are already subject to local restrictions will automatically move into the high alert level. As a result of rising infection rates, Nottinghamshire, East and West Cheshire and a small area of High Peak will also move into the high alert level.
“The very high alert level will apply where transmission rates are rising most rapidly and where the NHS could soon be under unbearable pressure without further restrictions. In these areas, the Government will set a base line of prohibiting social mixing indoors and in private gardens and I am sorry to say closing pubs and bars.
“We want to create the maximum possible local consensus behind this more severe local action, so in each area we will work with local government leaders on the additional measures which should be taken. This could lead to further restrictions on the hospitality, leisure, entertainment or personal care sectors, but retail, schools and universities will remain open.”
Rother Valley Conservative MP Alexander Stafford, and Labour MP for Barnsley Central - and Sheffield City region mayor Dan Jarvis - both confirmed South Yorkshire would be placed in tier two, while Colne Valley MP Jason McCartney said West Yorkshire would also fall under the same category.
But Shipley Conservative MP Philip Davies hit out at a "blizzard" of "arbitrary rules" and asks the PM to put his trust in the common sense of the British people.
He said: “One of the many reasons the Prime Minister has proved himself such a formidable and popular politician over so many years has been his resolute belief in the common sense of the British people.
“Therefore, instead of a constant blizzard of arbitrary rules which will only serve to collapse the economy and destroy businesses and jobs, will he instead remind people what’s important, social distancing, washing hands, the groups who are most at risk, the elderly, people with health conditions, etc and once again put his trust in the British people to act responsibly.
“After all, believing that individuals make better decisions for themselves, their families and their communities than the state can make for them is surely at the heart of what it means to be a Conservative?”
Mr Johnson replied: “He is exactly right and the best decision that individuals can make for themselves, for their families and for communities is to follow the guidance, wash your hands, face, space, protect the NHS and save lives.”
Mr Jarvis said: “We cannot afford this without additional support – otherwise we will languish in local restrictions with no clear way out.
“We’ve put a plan to Government and are awaiting more details.”
While Thirsk and Malton Tory MP Kevin Hollinrake confirmed the tier one, or medium, status for North Yorkshire.