We had a client who had a biometric appointment scheduled by USCIS for 12/24/2018. On 12/18/18 President Trump filed an executive order giving all Federal employees off for the 24th based on the discretion of the Department Head.

I called the local USCIS office and asked about biometric appointments. They told me that their office IS closed on 12/24/2018 and that anyone who has a biometric appointment scheduled will receive an new notice of appointment automatically.