My mutt does not like them at all and has a weird way of showing it. When lightning followed by thunder hits close he usually runs out in the backyard all bristled up barking at it, other times he finds a nice hiding place in the house.
What does your pet do?

My dog wines and cries untill i hold her or let her sleep in our room.

Mine hide and shake. I just give them a benadryl

Our black lab is a chicken heart during the storms. She sleeps in our room next to the bed.

If my wife is home, he acts very scared (shaking like he’s freezing, tries to hide in a closet, etc). She’s out of town and he acted much less nervous and scared this morning. It might be because she tries to calm him down whereas I just ignore it and it doesn’t add to his anxiety like trying to comfort him does.

Had several pointers that had dozens of quail shot over them but were still afraid of thunder and fireworks.

same here
in fact, they love shotguns

Yes

A Boeing 747 could crash land on our sofa, and Kimber would sleep thru it.

Haha good dog!

I have one dog four cats and everybody's stays pretty mellow.

My 140 pound Great Dane/Boxer mix would moan and shake when He heard Thunder and I'd get down in the floor and hold Him. Big Puss. Hopper went everywhere with us and slept beside our Bed for 16 years until I lost him about 4 years ago. This a shot towards the end. Smartest Dog I've ever owned. Still miss that Guy.

Mine doesn’t care if it storms. He just won’t leave the porch if it is

Blue my bird dog shakes and cowers in the corner.
Jack my police dog runs around the yard in the rain ready to play and doesn’t care about anything.

Watch out, he’s vicious

only my ants

Killer right there.

Almost exact behavior from my female border collie. When she's not barking at the thunder outside, she's pacing the whole house like crazy. Claw on wood floors all night...ugh.

Glens, he was a great lookin! Pup!

My Healer bristles and barks aggressively at it. I think he'd make a good military dog.

Muffin is not afraid of thunder but she does the same thing to robo calls.

My boss brings his Aussie Shepard to work everyday. She is terrified of thunder. She's been shaking like Michael J Fox all morning.

No but they freak me out.

Izzie snores right through storms. Dewey will jump in bed and glue himself to me. Sparkey doesn’t seem to care.

Our critters don’t have a problem with heavy weather, but they do hate loud noises - tractor, me shooting, etc.

Used to work with a woman that had a big dog (the breed I can’t remember) that actually chewed a corner off their wooden house during some bad weather when they were away and hadn’t put him in the house. She later asked me, if she brought the dog to the ranch, would I shoot him. Seriously. I cleared up her thinking on that.

And I had this cute little co-worker that said she was terrified of thunder and lightning and would hide in the back corner of her closet. I know that a number of you protective gentlemen would have volunteered to comfort her during her time of terror.