[diggan]

> Immediately after the maintenance, users will only be able to access Public PAIR through URLs beginning with HTTP, such as http://portal.uspto.gov/pair/PublicPair. Past URLs using HTTPS to access Public Pair, such as https://portal.uspto.gov/pair/PublicPair, will no longer work.

So it seems that the maintenance will turn of HTTPS, not that it's unavailable during the maintenance.