This is a very non-scientific method!! Take this anecdote for what it’s worth, but here is an update to my original post about the Synology box in my fireproof safe. Notes: safe has been opened at least every few days, the AC is running at times in my home, the windows open others. So just my observations, not a bulletproof study by all means.
I have been running the Synology two bay disk station in my Liberty safe for about 6 months now. Here in Michigan we are into the summer warmer months. I’ve included two charts of the internal disk temp and the temp inside my home for the past 60 days. The safe seems to be large enough to circulate the air and keep the temp within normal spec. I’m confident enough to keep this setup running as is year round as the NAS hardware and drives seem to be just fine.