Wales will go into a “short, sharp” national lockdown from Friday until 9 November.
People will be told to stay at home and pubs, restaurants, hotels and non-essential shops must shut.
Primary schools will reopen after the half-term break, but only Years 7 and 8 in secondary schools can return at that time under new “firebreak” rules.
Gatherings indoors and outdoors with people not in your household will also be banned.
First Minister Mark Drakeford said the “time-limited firebreak” would be “a short, sharp, shock to turn back the clock, slow down the virus and buy us more time”.
Without action the NHS would not be able to cope, Mr Drakeford told a press conference.