Hi and welcome to YT
. Melatonin can be used for storm anxiety and works well for some...you'd just need to give it ahead of the storm coming, so you'd want to know the weather. If you want to try it, you get the normal-release Melatonin, 3mg (don't get sustained-release)...you can get it at Target, Walmart, Walgreens, wherever.
I wouldn't hesitate to try prescription meds though, if it were me. I'd rather my babies feel less anxiety and if meds did that - I'd give 'em in a heartbeat!