I have an empty 20 gallon long that I keep for my hospital/quarantine tank. When its not in use I keep it out in my garage. But I just realized, can cold weather affect the silicone or anything? Its been getting pretty cold lately, down into the 20s and 30s at night. Just wondering if it would be better off being stored inside?

I would keep it inside. if its getting below freezing it might cause a problem

wow.. here it is about 30 degrees celcius on Australia. lowest it usually gets is about 15 degrees celcius

That is in Brisbane