This is a perfect vest for April to October around the Portland area. Don't expect it to shut out winter, but if you need a vest on a long cold summer descent, or you're just not sure if the sun you see outside means that it's warm out past your driveway, or actually that you will freeze as soon as you get out of town, this is the ideal vest. Functionally it takes the place of sluffing newspaper down your jersey (who has newspaper lying around anymore, or for that matter a jersey that's loose enough to fit a newspaper), is reusable (what do you do with Newspaper once you get to the bottom of the hill? Throw it on the side of the road for the tifosi to pick up, of course) , and, importantly stuffs down small to go into a pocket or handlebar bag. Works really well for the PNW non-summer summer days.