When you know you will be shooting in poor weather, use an oven bag or slow cooker bag to cover the camera. They are very durable, come in many different sizes, do not allow the moisture pass to the camera side of the bag, they are CLEAR so you can see everything including the flip out screen and they are darn cheap.
For a hand held cam (Panny 170, Sony NX5 class) the Reynolds brand slow cooker bag, sized 21 in x 13 in covers perfectly. They are 4 for $2.50/ish at any grocery store. Cover the long way and you will have unrestricted access to all controls and the drip line will be lower than the camera. Cut a hole for the lens, gaff it to the shade and done. You are in business.
I did this for a concert festival shoot yesterday. Rain for 6 hours out of the 9 I was there. Camera was bone dry all day. When it did let up I could pull the bag back a bit as needed.
For extra protection I used Cameragod’s tip of a shower cap on the lens when moving locations. Easy on and off. Kept the lens dry if it got pointed up while moving around in the golf cart.
Recap. Oven bags are cheap, durable, see thru, disposable and up to the challenge to keep your gear dry.