Customers took to Twitter to vent their anger after many were unable to withdraw cash or transfer money online.
NatWest customer Mark Hillman had planned an evening out last night, but it was cut short when he was unable to withdraw any cash.
He said: "I went from a night out to staying in, because I couldn't get my hands on my cash."
More top news
Temperatures recovering over the next few days.
An ambulance crew member told ITV News waiting outside hospitals to offload patients has become 'completely soul-destroying'.