Monday marks the first day of the “Summer of Hell” for Penn Station commuters.

A massive, eight-week track reconstruction program will affect those who depend on New Jersey Transit, the Long Island Rail Road and Amtrak as riders see a 20 percent reduction in service through Sept. 1.

About 7,400 NJ Transit riders on the Morris & Essex Lines will be forced to transfer in Hoboken weekdays after 7 a.m. instead being taken directly to Midtown Manhattan. The diversion is expected to add 30 to 45 minutes to commutes.

PATH will accept NJ Transit tickets at Hoboken, 33rd Street and the World Trade Center stations, according to Amtrak Chief Operating Officer Scot Naparstek.

The LIRR intends to add 36 cars to its trains, according to the MTA. Riders can also expect new ferry routes from Long Island to Manhattan to make room for an extra 2,300 commuters.

Two hundred extra buses will join existing service from Long Island into Manhattan.

Meanwhile, six Northeast Regional Service trains between New York and Washington, DC, have been canceled altogether. Six Empire Service trains will run between Albany-Rensselaer and Grand Central Terminal instead of Penn Station.

The embattled hub, owned by Amtrak, was forced to move up planned service work following three derailments, sewage showers and other nightmarish embarrassments over the past year.

With Post wires