Where do you store your cold wallet? A safe in your house? Also, where do you store your backup recovery phrase? Seems risky to store them both in the same place right? Fire could take both out.
I'm glad you've got your thinking cap on. Very few people consider the risk of natural disasters.
A first step you could take is implementing fire and water-resistant housing.
The "Cryptosteel Capsule" is the most popular solution I've seen.
A cheaper means to the same ends is to store encrypted copies of your backup in multiple physical locations. You could keep one in your safe at home, one with a trusted family member, one in your safe deposit box at the bank, etc.
Depending on the amount, you might even want to start memorizing seed words rather than recording them down in tangible forms.
I wouldn't risk trusting memory. Mine has devolved so much just in the years I've been using Bitcoin. I no longer have any faith in my ability to remember 12 words in specific order for any significant period of time. And then there is the risk of things like head injuries too.
I prefer the idea of hiding words in plain sight, using means of pattern recognition that only you -- and not an adversary -- can recognize.