Instructions
Look for trees, bushes, awnings, homes or buildings to block some of the rain and wind in order for your dog to "do his business."
Hold an umbrella over your dog to stop the rain from falling on her back and face. There's still the issue of wet ground, but keeping the rain off is half the battle.
Consider purchasing a dog rain coat. There are a variety of styles in a variety of price ranges--all with the same purpose--to keep your dog dry. And if you have a larger dog, you may consider purchasing a small foal (baby horse) blanket. These are waterproof, wind resistant and have velcro straps to stay in place. Many people with larger dogs find that these work well (see Resources below).
Consider a pet umbrella. Yes, you read right. This is an umbrella/leash combo that attaches to your dog's collar to keep the rain off. It solves the problem of you getting wet having to share your umbrella with your dog. And if you're worried that your umbrella may clash with your pooch's--the same company makes a human umbrella to match! (See Resources)
Try dog rain boots if you think your dog can handle it and won't raise too much of a fuss. There are a variety of styles from simple pleather to more sophisticated ones with adjustable ankle straps and non-skid soles (see Resources).
Now that your dog is good to go, you don't want to have to cut the walk short because you're not. Make sure you have on waterproof shoes and look for a waterproof (not water resistant), hooded rain slicker. If you're carrying an umbrella, the kind with an automatic pop-up button makes it easier to operate with one hand.
How to Walk a Dog in Rain
Some dogs don't mind walking in the rain, but unfortunately, most do. And if the dog lives in an apartment or doesn't have a yard, what's the alternative? Hold it in until it stops raining? Don't think so. May work in Southern California, but no such luck in Seattle. Here are some ways to get your dog to not mind so much--and perhaps even enjoy--a walk in the rain.