the Arc'teryx Accelero isn't waterproof, so it won't keep you dry when it is raining. It will shed a light drizzle, but it's really built to block some wind and wick moisture off your skin or baselayer.A good jacket to inspect for a combination of water resistance (if you buy a waterproof jacket for Extreme Power Walking you'll end up soaked from sweat, as truly waterproof jackets can't keep up with really high output sweating) is the Arc'teryx Venta LT. The Venta LT is made with windstopper, which is highly water resistant, but with a highly breathable material under the arms for excellent breathe-ability and moisture transfer. I'd recommend the Gamma LT pants for water-resistant, or the Alpha LT for waterproof pants (make sure the pants have vents if you're getting extreme)