If it's severe, then I'd be watching her and trying to make sure she doesn't wander off and pee or poop inside the house. Hailstorms up here are usually over pretty quickly and Ranger is full grown, so it's not a big deal to him if he has to wait for a little. He once held it in for 10 hour because it was pouring rain and princess didn't want to go outside. But with HIM, I know he's not going to wander off and pee somewhere.
I'd say probably your best bet would be to build a little sheltered area in the backyard so you could take her out there and not have to worry about hail/rain, etc. Or if you're in a condo, find a little overhang that you can dash to when it's potty time in bad weather. But definitely don't give the okay to pee/poop in the house when it's raining. I know at least 2 dogs that were allowed to do that a few times and now do it whenever it rains, despite being outside.
On that note, the only time I don't make Ranger go outside - sometimes I have to wheelbarrow him outside in inclement weather - is when it's hailing hard. We get frequent hailstorms here but they're usually little pieces and over within 15 minutes. Last summer, we got HAMMERED with hail out of nowhere...a bright sunny day turned pitch black and it hailed for 20 minutes. There was no way I was letting Ranger go outside in that!
This is how dark it was at noon on a summer day...and yes, those are hail balls on the ground:
Actual golf-ball sized hail
Damage it did to my truck - can't imagine what it would have done to Ranger. He was outside on a walk with his dog walker when a similar storm hit them 30 minutes before it hit home - luckily she'd taken shelter under a tree!
Weather like that, Ranger and I both stay inside!