There will be less frequent Manhattan bound service at High Street this weekend — late tonight until early Monday morning, April 24 — (but more Manhattan bound service at York Street in DUMBO) as Manhattan bound C trains will be re-routed to the F line between Jay Street-MetroTech and 34th Street-Herald Square. There will be more frequent service in both directions at Court Street and at the N/R platforms at Jay Street-MetroTech, as N trains will be re-routed to the R line all weekend.
The following work week — Monday morning, April 24 to Friday evening, April 28 — there will be no late night 3 train service in either direction at Clark Street or Borough Hall. 2 trains will make all 3 stops between here and Franklin Avenue-Medgar Evers College, and 4 trains will make all 3 stops between Atlantic Avenue-Barclays Center and New Lots Avenue. There will be no late night Manhattan bound service at High Street, as Manhattan bound A and C trains will be re-routed to the F line between Jay Street-MetroTech and Canal Street.
Always check MTA Info for 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.