I don't have space for them in the house and with my toddler it would be a recipe for disaster, it is very hot and sunny here in TN in case that matters!
As long as I can use them for the next year and a half or so that is all I need, they don't need to last forever.
Are your dumbbells vinyl covered? Your biggest issue will be rust. You might want to buy a cover? Patio covers (for chairs/lounges/etc) may be able to fit with a little tucking.