Last time it rained, it wasn't hard so I didn't use anything and I just got a little wet. ATR has a high wing so for the parts of the preflight where you spend the most time, you're under the wing.

If it pours, I'd just grab an umbrella from the closet. We keep a bunch there.

No big deal, really. Who cares what you look like with an umbrella. I'd rather stay dry than sitting in the cockpit drenched. And I never shelled the cash out for an overcoat. And I'd rather not have my hair and face soaked and then get in the cockpit and have it drip all over the paperwork.

Get an umbrella and be over with it.