They'll close if the rain is particularly bad, only because most people won't come in and it wouldn't be worth the expense to open. However, they do update their website if they'll be closing that day. So, be sure to check their website before you leave.
I would call ahead if they have a contact number listed.
Last time we went an awful storm came through we were given a card/free pass for next time.
I'm honestly not sure. They may have that information on their website though
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