Before refrigeration, it was nearly impossible to brew beer in the summer due to the hot weather and bacterial infections. Brewing ended with the coming of spring, and began again in the fall. Most were brewed in March (Märzen). These brews were kept in cold storage over the spring and summer months, or brewed at a higher gravity, so theyd keep. Märzenbier is full-bodied, rich, toasty, typically dark copper in color with a medium to high alcohol content.
The common Munich Oktoberfest beer served at Wies'n (the location at which Munich celebrates its Oktoberfest) contains roughly 5.0-6.0% alcohol by volume, is dark/copper in color, has a mild hop profile and is typically labeled as a Bavarian Märzenbier in style.