Visitors wearing traditional Bavarian clothes clink beer glasses in the Hacker-Pschorr tent at the Oktoberfest 2013 beer festival in Munich, Germany Sept. 22, 2013.
camera (Johannes Simon/Getty Images) Visitors wearing traditional Bavarian clothes clink beer glasses in the Hacker-Pschorr tent at the Oktoberfest 2013 beer festival in Munich, Germany Sept. 22, 2013.

The beer starts flowing today in Munich's 181st Oktoberfest, which ends October 5.

Why is Oktoberfest called "Oktoberfest" when it really begins in September?

That's a frequently asked question on the website Oktoberfest.de.

And here's their answer:

The historical background: the first Oktoberfest was held in the year 1810 in honor of the Bavarian Crown Prince Ludwig's marriage to Princess Therese von Sachsen-Hildburghausen. The festivities began on October 12, 1810 and ended on October 17 with a horse race. In the following years, the celebrations were repeated and, later, the festival was prolonged and moved to September.

Women wearing the traditional dirndl take part in the traditional costume parade of the Oktoberfest beer festival in front of the Odeons church in Munich, Germany, Sept. 22, 2013.(Christof Stache/AFP/Getty Images) Women wearing the traditional dirndl take part in the traditional costume parade of the Oktoberfest beer festival in front of the Odeons church in Munich, Germany, Sept. 22, 2013.

By moving the festivities up, it allowed for better weather conditions. Because the September nights were warmer, the visitors were able to enjoy the gardens outside the tents and the stroll over "die Wiesen" or the fields much longer without feeling chilly. Historically, the last Oktoberfest weekend was in October and this tradition continues into present times.

- Oktoberfest.de

Revelers dressed with traditional Bavarian Lederhosen trousers enjoy drinking beer during day 2 of the Oktoberfest 2011 beer festival at Theresienwiese, Sept. 18, 2011 in Munich, Germany. (Johannes Simon/Getty Images) Revelers dressed with traditional Bavarian Lederhosen trousers enjoy drinking beer during day 2 of the Oktoberfest 2011 beer festival at Theresienwiese, Sept. 18, 2011 in Munich, Germany.