I am planning to go to Florence in September and I'd like to know if September is going to be a busy tourist season and if it is necessary to pay extra to reserve advance tickets to 1) The Accademia Gallery, and 2) The Uffizi Gallery. This will be my first time to Italy and any feedbacks will be greatly appreciated!

The reservation fee is 4€ if you book directly with the museums. The Uffizi has a special exhibit that runs thru the end of September so tickets include that and will be 6.50€ + 3.50€ (exhibit) + 4€ (reservation fee).

It somewhat depends on when in September you'll be visiting. We'll be in Florence in late September, and I recently noticed that reserved times for the days that we'll be in Florence for the Uffizi are already starting to get full - so we booked those ahead.

For the Accademia, I wouldn't be so concerned.

I would definately get reservations for the Uffizi. There are two lines that get you into the Uffizi--one for reservations which takes you about 2 minutes to get through and "THE OTHER" which I do not know how long but it had about 100 people in it. They only let a number of people in at a time. The day you have your reservation, you go to a place and pick up your tickets, go to the line that is for reserved tickets, and presto you are in within 5 minutes.
I agree, the Accademia is no problem.

Thanks! Does anyone know how much is the ticket for Accademia?

6.50€ + the 4€ reservation fee.
http://www.polomuseale.firenze.it/en...sei/accademia/

It looks like you are framing necessity in terms of chance of a long line or not?

Would you have a different answer if you frame necessity in terms of Uffizi and Accademia being not to be missed museums? Is €8 total reservation fee a worthwhile investment for you to ensure you can get into these museums irrespective of there is a long line or not?

These are the questions only you can answer.

If you frame necessity in terms of whether there is a waiting line or not, then you are at a mercy of probability. If you read this forum, you will find quite a number of people who could not get in.