If I lived in a rainy climate and wanted an outdoor bench without constant upkeep, I’d skip traditional wood and choose HDPE lumber, often called poly lumber or all-weather plastic lumber. It’s the best low-maintenance outdoor bench material for wet weather because it won’t absorb water, rot, warp, splinter, or rust. Rain simply beads on the surface or drains through the gaps. You don’t need to seal, stain, paint, or sand it. An occasional wash with soapy water is all it takes.
Powder-coated aluminum is another excellent rainy climate bench choice. Aluminum won’t rust like steel, and a thick powder-coated finish resists corrosion and chipping. It’s lightweight and easy to move, but check that the hardware is stainless steel or marine-grade. Cheap steel bolts can rust and leave streaks on the bench or patio.
If you love real wood, teak is the classic low-maintenance option. Its natural oils make it highly rot-resistant, and it can survive outdoors for decades. However, in a rainy climate, teak will weather to gray and may collect mildew or algae on the surface. That’s not structural damage, but you may need to clean it occasionally if you care about appearance. I’d call teak low-maintenance, not zero-maintenance.
Avoid untreated softwoods, standard pine, iron, and bare steel unless you enjoy sanding and repainting. Basic composite wood can be okay, but cheap uncapped composites may absorb moisture and develop mold in consistently damp conditions.
If you want the closest thing to a set-it-and-forget-it bench, pick an HDPE outdoor bench. It’s heavy, durable, and built for weatherproof bench performance in rain, snow, and humidity. If you prefer lighter weight and a metal look, choose powder-coated aluminum. If real wood matters most, choose teak and accept the patina. Whatever you pick, make sure the seat has drainage slots or spaces between slats so water doesn’t pool, and use coated or stainless fasteners.