With Rocky Mountain weather in its typical state of constant flux through February and March, Allison Pattillo decided it was the perfect opportunity to test a bright bouquet of lightweight running jackets—all built with the same purpose of warding off spring breezes, summer drizzles and fall chill. “Lightweight,” is definitely the key word here, as none of the jackets tested weight more than four packets of Peanut Butter GU. All the models feature a full-zipper, wind resistance, breathability and water resistance, and can easily fit in your pocket or pack. Many also mix in some bells and whistles with obvious benefits. Read on to pick the right one for your next run.