If you're not sure whether it's cold enough to run in a jacket, just throw on the ventilated Oakley 3rd-G Zero Shield 2. 0 Jacket and stop wondering. This lightweight running shell provides water-resistant protection against drizzly showers and lighter snows, and does so with enough breathability to really help you kick it into a higher gear in your training. You've got tiny laser holes on the front shoulders to let the air in when you're zipped up tight, as well as perforations under the sleeves to help dump heat in effective areas. A fixed hood delivers coverage and protection from wind and rain, while reflective accents at the sleeve cuffs ensure visibility during those low-light runs in late fall. Plus, with its full-zip design this jacket easily accommodates baselayers and midalyers, making it a reliable option well on into the winter as well.