Regarding the hand-held air horns, what temperature range are they good for?

Will they freeze up?

Do high temperatures cause the gas inside do seep out?

Thank you very much.

Good question.

I think you'd need to look up the manufacturer of a specific product to get definitive answers.

Here's a link to one manufacturer. I've seen their products around but never used them. There's a link to the MSDS for the propellant here as well.
http://seasense.com/index.php?page=shop....t&Itemid=26


Here's a very interesting marine air horn that doesn't use a cannister at all. Might be better than any whistle out there.
http://seasense.com/index.php?page=shop....t&Itemid=26

Standard disclaimer: no affiliation.