The airline had intended to cancel 20 due to the bad weather but went on to ground a further 80.
Today, British Airways has already axed at least 79 arrivals and departures at Heathrow because aircraft and crew are out of position.
The cancellations are due to affect at least 12,000 passengers. Long delays are also to be expected.
All the grounded flights are short-haul, with Milan, Geneva, and Barcelona hit by multiple cancellations.
BA passengers are being urged to check the status of their flight before they leave for the airport.