Check out the “Let it Snow” Xmas 2020 Group youtube project!”
An interesting question, @Mouse .
The wood should be fine. If it got really hot, the varnish might soften and stick to the case fabric (or dust might adhere to it if left on a stand). The bow hair will likely tighten in a highly humid environment. All of the above are minor considerations.
The area of most concern is hand sweat migrating into the threaded portion of the frog button and rusting the nut to a fixed position. This is s fsirly common situation.
Without deviation from the norm, progress is not possible. —Frank Zappa
The future is already here—it’s just not very evenly distributed. —William Gibson
High humidity will cause bow hair to stretch (and loosen), not tighten -- this also means you should loosen the bow before bringing it back into an air-conditioned room.
But otherwise Irv is correct. The wood should be fine. The varnish on the bow might not be, especially if playing in direct sunlight.