First, some good news. The Momtague Street entrances to the Court Street station on the N/R le are open again; see photo taken yesterday.
This weekend — this (Friday, June 16) evening to Monday, June 19 morning — there will be no service in either direction at the 4/5 platforms at Borough Hall, as 4 trains will originate and terminate at Bowling Green in Manhattan, and 5 trains do not serve Brooklyn on weekends. 2 and 3 trains should be reunniung normally, except that 2 trains will be on a reduced schedule, running every 12 minutes. Those traveling to or from the East Side of Manhattan can switch between a 2 or 3 and a 4 or 5 at Fulton Street. Those traveling to or from Brooklyn can take a 3, which will be making all 4 train stops. Once again there will be extra service at Court Street and at the N/R platforms at Jay Street-MetroTech, as N trains are being re-routed to the R line all weekend instead of just late at night.
The following work week — Monday, June 19 to Friday, June 23 — there will be no late night service at High Street and extra service at York Street in DUMBO, as A and C trains will be re-routed to the F line between 4th Street-Washington Square and Jay Street-MetroTech. Late nights Monday to Tuesday and Tuesday to Wednesday there will be no service at Clark Street or at the 2/3 platforms at Borough Hall, as 2 train service will be suspended between Chambers Street in Manhattan and Atlantic Avenue-Barclays Center, and 3 trains do not serve Brooklyn late at night. Use 4 trains as an option, transferring at Fulton Street in Manhattan or at Atlantic Avenue-Barclays Center. Late night Wednesday to Thursday there will be no Brooklyn bound service at Court Street or at the N/R platforms at Jay Street-MetroTech, as Brooklyn bound N trains will be re-routed to the Q line between Canal Street in Manhattan to DeKalb Avenue in Brooklyn, and late night R train service will be suspended in both directions. Manhattan bound N trains should be running normally.
Always check MTA Info for last minute changes in planned service or unplanned service changes that may affect local service or service on other parts of your trip, or for planned service changes that affect stations to or from which you may be traveling. You can also get real time service alerts: register here.