A still from Kmart’s controversial new Christmas ad. (YouTube)

It’s only September, but Christmas is in the air — or, more accurately, in the airwaves, where Kmart just premiered its first Christmas commercial of the holiday season.

The 30-second spot, which Adage says played multiple times on Monday, enraged Kmart’s season-conscious customers, who complained on Facebook by the hundreds that the retailer had stretched the holiday season to truly untenable limits. Some appeared to take it quite personally.

“It is SEPTEMBER! How dare you,” one woman wrote. “Maybe some people just want to enjoy life in the moment and be thankful for that rather than always rushing through. Doesn’t life between now and the holidays matter? Why discredit it and take away it’s [sic] value by sticking the idol of a holiday in it’s face?”

Kmart, to its credit, was probably not trying to undermine the existential value of the autumn months. The commercial is for the store’s holiday layaway program, which lets people pay off big, expensive purchases in more manageable chunks (and which launched already at Walmart and Toys ‘R’ Us last month).

Also, the Christmas season has started. Every year around this time, people slowly begin searching for, and tweeting about, holiday-related things. The chart below shows Google search volume for the word “Christmas” every year since 2004: The big spikes arrive in December, of course, but those first glimmers of interest, where the steepness of the line begins to pick up, start now.

(Google Trends)

It’s the same on Twitter, where people — particularly celebrities — begin dropping holiday plans months in advance. And this isn’t just an Internet phenomenon: cable channels TCM, Starz Kids, Encore, Disney XD and E! will all air Christmas movies this month, according to CountdownUntilChristmas.com, a Web site that exists solely to track when Christmas movies air. A poll of more than 1,300 visitors to the site found that almost three-quarters watch Christmas movies long before Thanksgiving. (Of course, people who take polls on a site called “Countdown to Christmas” are probably not representative of the population as a whole.)

Sales of eggnog pick up in October. Finance magazines and services frequently begin running their holiday savings stories in September, when people come back from summer vacation and start to plan out the rest of the year. Many experts say the weeks after Labor Day are the best time to book holiday airline tickets.

In fact, far from the crime against tradition and decency that some are making it out to be, talking about Christmas in September is actually pretty smart. It helps avoid the last-minute, merriment-crushing stress the holidays often bring — and the financial unpreparedness that pulls many shoppers into debt on January 1.

That latter motive is, of course, the idea behind Kmart’s layaway program, which is designed to help people pay for gifts over time. But don’t tell that to the angry Scrooges who just want to enjoy September. Many of them are vowing to boycott the store entirely.