The terminal was meant to be operating normally on Saturday
Snow has led to more than a 100 flights being cancelled at Heathrow's Terminal 5 as scuffles reportedly broke out between passengers and staff.
The bad weather added to the disruption at the airport where the opening week was blighted by baggage delays.
Passengers reported seeing frustration boiling over as travellers tried to board buses to and from the terminal.
A total of 185 flights across Heathrow's five terminals have been cancelled due to bad weather.
Wintery weather has affected flights right across Europe.
Of the flights cancelled to and from T5, 12 were still due to technical problems with the baggage system.
BBC reporter Joe Lynam, who spent the day at Heathrow, said one passenger told him she had seen scuffles break out between frustrated passengers and staff as they were trying to get on and off buses inside the airport.
A BAA spokesman said he has not had any reports of such incidents.
Baggage handlers had worked through the night sorting bags by hand because of a software fault in the automated system operated by BAA.
The software problem was fixed in the early hours of Sunday and the baggage system is now functioning well, according to the BAA spokesman.
But the bad weather meant two runways had to be briefly closed after heavy snow fell in London between 0700 BST and 0800.
"This meant we had to put the snowblower and snowbrusher vehicles out to remove the snow from the runways reducing the number of aircraft that can take off and land at Heathrow."
On top of this the BAA spokesman said the airlines have to de-ice their aircraft before taking off which takes up more time than usual.
The snow has also led to the cancellation of 51 BA flights at Gatwick.
The terminal suffered baggage problems within hours of opening 10 days ago, but BA had expected to operate a full schedule of flights for the first time on Saturday, having said the problems were resolved.
However, it ended up cancelling 24 flights when the automated system malfunctioned.
A spokesman for BAA, the airport operator, said on Saturday night: "We are sorry for the inconvenience this may cause to British Airways and passengers."
Since the terminal opened, hundreds of flights have been cancelled because of glitches with its new baggage-handling system, a temporary suspension of luggage check-in and staff familiarisation problems.
It is thought that about 9,000 bags still need to be returned to their owners - down from 28,000 which were delayed during the past week.
The airline said its problems were expected to cost it about £16m.
BA says it will contact all passengers on cancelled flights who have given BA mobile contact details.
But all passengers are advised to check the BA website before travelling.