Hello! I will be arriving on a Delta flight at around 8:05 AM. Based on the given strike information so far for weekdays and given that I will be coming through passport control, will I be able to take the RER B from CDG to Gare du Nord before 9:30 AM? If not, will I still be able to wait and catch an RER B train sometime that morning?
RER B trains from CDG to Paris city center will run throughout the day during the December 2019 train strikes without interruption, just with reduced frequency from normal RER train times and impacting off-peak hours more than peak-hour trains.
You'll still be able to catch RER B trains from CDG Airport into the city after morning peak hours end at 9:30 a.m. RER B trains will continue to depart CDG for Paris during the strike at 10:06 a.m., 11:06 a.m., 12:06 a.m. etc. See the December 2019 Train Strike page for a full schedule of RER B trains from CDG to Paris.
Alternatively you can take a Roissybus from CDG to Paris Opera which is operating at 4/5th normal frequency as opposed to 1/3 - 1/5 capacity like the RER B during the December 2019 train strikes.