The IRS will automatically give you the extension based on your address.
However, this only applies if you had an approved extension to October 15, 2017. If you don't have an approved extension already your taxes were due April 15 and this does not change that.
Also note, your payment was still due April 15 even if you have an extension to file, so Harvey does not change any penalties you will owe for late payment.
And as explained in the other answer, you won't be able to use Turbotax Online after October 20.
