Disruption caused by the heavy snowfall could cost UK businesses around £1bn, business groups have estimated.
The Federation of Small Businesses (FSB) said that 20% of the UK's working population, or 6.4 million people, would not make it to work.
South-east England has the worst snow it has seen for 18 years, causing all London buses to be pulled from service and the closure of Heathrow runways.
Trading on the London Stock Exchange was thinner than normal.
Stephen Alambritis from the FSB said its estimate of £1.2bn was a cautious one and the actual cost was likely to be higher.
"There is also the knock-on effect of passing trade going down as people won't be buying their sandwiches for lunch or picking up a coffee or newspaper," he said.
Shares in transport companies fell on the stock exchange, with trading volumes slightly lighter than normal as dealers struggled to their offices.
British Airways, which has cancelled all flights from Heathrow, was down 4.25% at 115 pence, while Go-Ahead, which runs Southeastern rail services, was down 2% at 963.5p.
Royal Mail collections and deliveries have also been disrupted.
Disruption
The Centre for Economic and Business Research said that UK economic output or gross domestic product per day is about £4.5bn.
"So if 20% of the population have zero productivity for the day, there is a loss of £900m," said Douglas McWilliams, CEBR's chief executive.
He added that companies' cashflow could be hit by delayed payments as a result of the disruption and this could mean that an additional 2,000 to 3,000 businesses may fail as a result of the bad weather.
"Many of the businesses that are close to failing are in the retail and construction sectors that are likely to be most affect by the snow and transport disruption," he said.
Short-lived?
Dr Helen Hill, director of policy and public affairs at the London Chamber of Commerce and Industry said that a one-day closure of the Tube can cost the capital £48m in lost productivity.
"Hopefully things will not grind to a halt completely however, as local staff may be able to get into the office and many others can now work remotely and conduct business online," she said.
Howard Archer, an economist at research firm Global Insight, said that small businesses could be particularly vulnerable if core staff cannot make it to work.
However, he said that any hit to the economy would likely be short-lived.
"Some of the loss of business/trading may be quickly made up once the bad weather eases. Very cold weather will boost utilities output," Mr Archer said.
"But any disruption to business is the very last thing that the UK economy needs in its current extremely weak state," he added.
Keith Tilley, managing director of SunGard, which helps companies deal with unexpected events, said its clients had so far not faced too much disruption.
"Employers need to do everything they can to allow staff to work from home and ensure that those that do manage to travel to work are well looked after, with overnight accommodation if necessary," he said.
"Businesses need to do all they can to maintain normal service levels and ultimately avoid losing customers and revenue," he added.