What to do when it rains?

Puppy has been doing good going outside now! However now it’s pouring and she’s scared but when she goes inside like potty my grandma locks her outside in the rain for like 5-10 mins each time and i think that’s just not good? So how can i help her go potty outside in the rain so my grandma stops locking her outside. Do i use an umbrella and follow her?? Is it ok she goes potty inside since she’s barely 2 months? Any advice will help since it’ll rain the rest of the week