Grundéns Men's Neptune 319 Waterproof Hooded Commercial Fishing Jacket

Is this jacket genuinely 100% waterproof, or will it eventually leak in heavy, driving rain?

It is completely waterproof. Unlike standard "breathable" rainwear that can saturate and leak under pressure, the Neptune 319 uses a solid polyurethane-coated stretch polyester shell paired with heavy-duty welded seams to guarantee that water cannot penetrate, even during relentless downpours on a boat deck.

Does it have any insulation to keep me warm on cold, windy mornings?

The jacket is unlined and does not contain built-in insulation. It is designed to act as a 100% windproof and waterproof outer shell. For cold-weather trips, customers recommend purchasing one size up so you can comfortably layer a thick fleece or hoodie underneath.