It’s difficult to predict the weather for Oktoberfest. Some years it will be warm and beautiful, other times it will be cold and rainy. It’s best to pack a range of clothes.
When it is sunny and warm, you are probably looking at highs in the upper 70s. When it is cold and raining, you should expect highs in the 50s.
The average high in September in Munich is 66 degrees Farenheit. The average low is 47. The average high in October is 56 and the average low is 40.