People are being told to stay indoors until at least 3pm Friday, as a red alert for snow is extended for the whole country.
A band of snow from the East is forecast to clash with strong gusts from the South, creating a life-threatening blizzard.
The Taoiseach Leo Varadkar has said we won't have seen conditions like this since 1982.
All schools and colleges in red alert zones will stay closed for the rest of the week, as will many shops. An Post won't be delivering in Dublin until further notice.
There will be no Dublin Bus, LUAS or Irtish Rail services on Friday, and Dublin Airport has suspended all flights until Saturday.
Dublin City Council has closed all parks, leisure centres and libraries until further notice, and most shops are also shut.
As well as staying indoors, people are also being reminded to check on the elderly, and take pets in from the cold.
Additional reporting by Brendan O'Loughlin