Yes, Seed, I live in that town of the biggest beer festival. About 3km (2 miles) from the festival area, and every working day I pass by it.
And I hate the beer festival - I myself prefer wine, and it is such a mess with up to two million people (at peak times) on that small area. I usually try to take holidays during the beer festival to evade the traffic chaos, the stink (of pure beer, beer filtered through kidneys, beer which was drunk twice - once down and once up ...), the noise (during Octoberfest I have to turn up the volume on my TV to understand what is spoken), all the drunk people (up to last year I worked in a company about 200m (220yards) from the festival area, on the way to the city railway, and very often in the morning I had to use the backdoor to the office because the front door was blocked by drunk people sleeping in front of the doors).

About celebrating October in September: it is called Octoberfest because the festival traditionally ends on the first Sunday in October (and start two weeks before that). Nowadays it can last even longer, but only if the first Sunday in October is the 2nd of October, because then it ends on Monday, 3rd October (3rd October being our national holiday - the day of the re-union of east and west Germany)
But perhaps we celebrate October in September because "in Bavaria the clocks are working different" (In Bayern gehen die Uhren anders - a popular proverb here). You can actually buy "Bavarian" clocks where the watch hands turn anti-clockwise!