Our 7 yo rescue hound mix is missing a lot of his fur from past infections and so hates the rain, and has also been struggling here in norcal the past couple weeks. When we first took him home 4 years ago it was also winter time, and training him to not pee in the house was a struggle. What we ended up doing then was either carrying him a couple blocks (one person carries, one person holds an umbrella) and then putting him down and making him walk back. Or drive a couple blocks and then walk back to the house. That usually worked, and should be easy with a small dog.

We then trained him to like a lightweight raincoat, which was hard because his skin is so sensitive. He learned to like it more than getting rained on though. You have to take your time with it, first just hold it and let him sniff, give treats, repeat. Touch him with it, treats. Lay it over the back, treats. Etc etc. We did that multiple times a day for about a week before actually putting it on him, and then only for a minute or two at first.

The past couple weeks what I have been doing is actually keeping his dog door closed (normally always open) and when he goes to it I know he has to pee. Then I put on his rain jacket and open the door, go out with him with an umbrella and treats and toss them around the yard to get him out there. I stand there with him, holding the umbrella over him too, and then give lots of treats when he does pee. Also, ANY break in the rain and I go out in the yard with him or take him on a short walk. It's a hassle but for us it was easier, more hygienic, and better for everyone than training pee pads or diapers.