Charles Dickens lived during the Little Ice Age, which is probably why White Christmas became a tradition!
Because of a Little Ice Age, it snowed during the first 8 Christmases of Charles Dickens' life. That’s why White Christmases are a consistent feature of his stories.
His snowy childhood has its origins in the colder climate of the period 1550-1850 when Britain was in the grip of a 'Little Ice Age'. Winters were particularly persistent and severe in 1813-14 was the last winter that a 'frost fair' was held on the frozen River Thames in London.
Before the change of calendar in 1752, which effectively brought Christmas day back by 12 days, snow was even more likely as Christmas comes at the beginning of the season for snow. Wintry weather is more likely in January.
So there you have it, White Christmases became a thing because the world was freezing when Charles Dickens was alive. Maybe now you won’t be so bummed if it doesn’t snow on Christmas day.