It's really nice of you to take care of Mor-Mor (沫沫) and also helping her to get into shape again.
We (dogs) need to run and have fun - if we are too heavy all the fun is gone.
I - personally - hate rain. I will not go outside if it rains. Even if I have to pee or 💩. No way that I will go outside into the rain!!!
When we are outside already and it starts to rain I will look for shelter even if it's not helping ...