Regions of New Jersey

North Jersey is the densest ground in the densest state, and almost none of it drains well. The Passaic and the Hackensack back up into Paterson, Little Falls and the Meadowlands on their own schedule, the Hudson waterfront floods on the tide when a nor'easter pushes water up the harbor the way Sandy did, and the urban heat island runs the Newark thermometer several degrees above the counties around it on a July night.

The northwest corner is the cold end of New Jersey and the only part of it with real relief: High Point reaches 1,803 feet and the Kittatinny ridge holds snow weeks after the shore has lost it. Storms that fall as rain on the Turnpike fall as ice here, the valleys pool cold air on a clear night, and the Delaware and the Musconetcong flood out of the hills fast.

Central Jersey sits on the seam where the coastal plain meets the Piedmont, and it is where the state's two weather regimes argue: the rain–snow line parks over the Raritan Valley more often than anywhere else in New Jersey. The Raritan itself is the state's biggest river basin and it has taken Bound Brook and Manville apart more than once — Floyd in 1999, Ida in 2021.

This is the coast Sandy came ashore on, and the barrier islands have not forgotten it. Everything here is a tide problem before it is a rain problem: back-bay flooding on Barnegat Bay puts water in Toms River and Manahawkin on a full moon and a stiff northeast wind, no storm required. The sea breeze also runs the summer forecast — it can hold the beach twenty degrees below Lakewood on the same afternoon.

The southern shore is the warmest and the most exposed ground in New Jersey — Cape May sticks four miles into the mouth of the Delaware with water on three sides, which keeps it mild in January and cool in July and puts it first in line for anything that comes up the coast. Inland, the Pine Barrens do the opposite: the sand drains so fast and radiates so hard that frost hollows near Hammonton and Estell Manor regularly post the coldest readings in the state.

South Jersey is Philadelphia's weather more than New York's, and its own inside the Pinelands. The Delaware Valley runs hot and humid in summer and sits on the wrong side of most of the state's snow, while the Pine Barrens behind it hold the state's record cold. The bay shore from Salem down to Fortescue floods on the tide, and Ida's remnants in 2021 put a tornado through Mullica Hill.