Lockdown restrictions are set to come into force in Cardiff and Swansea county areas and also the town of Llanelli.
They will come into effect in Llanelli, Carmarthenshire on Saturday at 18:00 BST and in Wales’ two biggest cities on Sunday from 18:00.
It will mean eight counties will be under lockdown and one town in a ninth.
On Thursday, there were 25 new cases in Carmarthenshire, 39 in Cardiff and 41 in Swansea.
Wales’ Health Minister Vaughan Gething said cases in Carmarthenshire had “overwhelmingly” been linked to Llanelli, with eight out of 10 cases there.
The majority have been linked to people socialising without social distancing.
This will be the first localised lockdown in a town in Wales, and he said Burry Port would not be included.
People living in Caerphilly, Rhondda Cynon Taf, Bridgend, Blaenau Gwent, Merthyr Tydfil and Newport already cannot leave their areas without a reasonable excuse, under rules in place.
The changes mean around 1.5 million people will be under local lockdown, a little under half the Welsh population.