The shops are full of it, the adverts have started and if you were one of the reported one million families who were in Oxford Street last weekend, you'll know that the lights are up and on. Christmas is well and truly on its way.
For the big switch on the stage was packed with home-grown musicians, including R&B singer Craig David, who performed to an Oxford Street packed full of people - and free of vehicles. The space normally dominated by buses and taxis had been given over to happy families and friends, shoppers, excited tourists and a host of entertainment.
There was a message of seasonal cheer too, as funds were raised for the NSPCC charity's Little Stars appeal through donations from people to name one of the Oxford Street lights in honour of someone important in their childhood, with money raised going towards keeping children safe and free to dream at Christmas.
As I shared my pictures and enjoyment of the day on Twitter, I saw it summed up nice and simply by another tweeter, 'Every day on Oxford Street should be like today!' - and I couldn't agree more, because amidst all the fun there was some serious work going on by King's College which revealed just why Oxford Street should - and needs - to be like that every day.
The closure to traffic was a great chance to demonstrate the difference in air quality - and in particular levels of deadly nitrogen dioxide. Coming just days after Client Earth won a High Court ruling that the UK government is not doing enough to tackle air pollution, this was timely.
Scientists at King's College had measured the air pollution levels every Sunday in September and October and taken an average. They then compared it with the NO2 levels when the road was closed to traffic for the switch on. And the results were undeniable.
Nitrogen dioxide levels in the air around Oxford Street dropped by a whopping 31 per cent just a few hours after the street was closed to traffic. It's this exposure to high levels of nitrogen dioxide that causes heart disease, stroke, lung disease and cancer, and is currently responsible for over 9,500 people in London dying prematurely. Traffic is on the rise. And children are especially at risk, so this is also about making children safe.
These findings show how much we stand to gain by making Oxford Street vehicle-free, as London Mayor, Sadiq Khan has committed to do by 2020. It can't come soon enough.
Crossrail opens in 2018, bringing with it an estimated 150,000 more people a day onto Oxford Street. Local businesses represented by the New West End Company have shown themselves open to progressive solutions. The Mayor, TfL and Westminster council need to take action soon, and it can't just start and end with Oxford Street.
Dr Gary Fuller from the King's College team said "Clearly Sunday's closure of Oxford Street led to a big improvement in air pollution for the shoppers," but he adds that the levels did not reach zero: "There was still traffic on the surrounding roads. This shows that solving London's air pollution hotspots requires action over a wide area."
And as Client Earth's case shows, the failure to tackle dangerous pollution levels is a nationwide problem - and people's lives depend on us finding a solution.
This is why our campaign to make Oxford Street one of the world's greatest public spaces does not end with its pedestrianisation. It is about more than paving and redirecting bus routes.
It is about putting people at the heart of Oxford Street and re-engineering how the whole area around it works.
It is about setting the standard for a walking city. And Oxford Street can act as a shining beacon.