Last month's heavy snowfall meant that airport operator BAA handled almost 11% fewer passengers at its six UK airports than in December 2009.
The company said the cost of the weather disruption was approximately £24 million.
A total of 7.2 million passengers passed through the six airports in December 2010 - a 10.9% drop on the December 2009 figure.
BAA handled 4.8 million passengers at Heathrow last month - a 9.5% reduction on December 2009.
The biggest dip last month was at Southampton airport where there were 22% fewer passengers.
Edinburgh was down 18.4%, Glasgow fell 15.3%, Stansted was down 10.9% and Aberdeen fell 8.3%.
BAA was heavily criticised for its handling of the snow crisis at Heathrow where thousands of Christmas getaway passengers had to camp overnight in the terminals as flights - at one stage - almost ground to a halt.
The company has set up an inquiry into its December 2010 Heathrow operation, with a report due in March.
Sir Richard Branson's airline, Virgin Atlantic, has said it is withholding some Heathrow charges until it sees the results of the inquiry.
BAA reckoned that the £24 million weather-related loss last month included a £19 million loss at Heathrow, a £1 million loss at Stansted and a £4 million loss at its four other UK airports.
BAA chief executive Colin Matthews announced last month that he would not be taking his 2010 annual bonus
He said today: "The coldest December on record closed airports around the world but we must carefully examine the snow plan agreed with airlines earlier in the year and strengthen it to protect against such unprecedented weather.
"We are sorry for the flights that had to be cancelled as a result of the snow. The cost of any disruption to BAA's airports is significant and a strong financial incentive for us to continue to make Heathrow more resilient."
Overall, BAA handled 103.9 million passengers in 2010 - a drop of 2.8% on 2009.
The company was hit not only by the December snow but also by two British Airways strikes and the Icelandic volcanic ash cloud crisis last spring.
BAA said today that these various events caused the loss of around 3.6 million passengers and that in a "normal" year passenger numbers would have increased by 0.6%.
Mr Matthews said: "There were many challenges in 2010, ranging from poor weather and security threats through to industrial action and the cloud of volcanic ash.
"But we have continued our £1 billion-a-year investment programme and are encouraged by Heathrow's underlying positive performance during challenging economic times.
"Heathrow has improved considerably in recent years, and we are determined to put December behind us and win back confidence by improving customer service, upgrading our terminals and doing whatever it takes to improve people's journeys."