The State Climatologist calls the shore a zone where land and ocean weather fight it out day to day. Nor'easters come through most often between October and April. Wind pushes the rain sideways, and a shingle that has lost its seal at the edge or the ridge lets it straight in.
Salt air does its damage slowly. It works on nails, flashing and drip edge, and a joint that looked tight last year can open up. Neptune's median house dates to 1963 and a quarter of Long Branch homes predate 1940, so a lot of shore roofs have flashing that was patched once already.
In Long Branch and Asbury Park, 1 home in 10 is a two-family house. Water that gets in upstairs can travel and show up on the downstairs ceiling. With your tenant's okay, we look in both units so the repair goes where the water starts.
So we do not patch under the wet spot and hope. We follow the water back to where it gets in and photograph it before any repair.