What’s the max ambient temperature the Hubitat C8/C8 Pro can tolerate?
Where is that info display located that you screenshotted, showing the C8 temperature? Is that a built in info panel, or an app?
It’s a driver
Are you asking what the hottest room could be? (AMBIENT = room or surrounding environment temperature?)
Or what the max operating internal temperature is? The latter is what is shown on the image that @rlithgow1 posted
The former has been discussed several times. Hubitat doesn't list those specs. But, the consensus is it would be the same range as any other computerized operational specs.
Handy. I have the driver installed, but I didn't realize I had to change the temp polling in preferences to get the temp attribute.
Now that I done so, I'm at 138.2 F 
I'm not surprised, this is my overloaded C8. The C8 Pro is still sitting on my desk, waiting for me to get around to doing the migration... Maybe that will happen this weekend 
Yes, I meant ambient = room/surrounding environment temp, ie, if I install a Hubitat in an RV that is parked in the desert (it has solar power to run a security system but no A/C while parked), and it gets to around 110F-120F in there for a couple months in the summertime, will that kill the Hubitat?
What’s the temperature of the room it’s sitting in when it’s at 138 F ?
I would expect that to shorten the hub’s lifespan.
There’s no published operating temperature range, but it’s a computer with no special environmental hardening. That’s very hot for any kind of consumer electronic device.
Yeah, I’m hoping I’ll hear from someone who’s actually tried it. “Shorter life”, like, it doesn’t last 5 years, I could live with. “Shorter life”, like it dies in a week, that would not be good of course.
Generally I’d assume the max operating temp to be somewhere around 158F, typical of many routers and mini PCs, then it’s just a question of how much heat the C8 retains.
I’ll install that driver that @aaiyar linked to and see how it’s behaving in different scenarios.
Would be very nice if there was chunky-heat-sink variant of the C8. Those of us in the Southwest USA consider 110F to be a nice breezy summer day in July/August… 
It is on the top shelf of a small hallway closet, along with my router. I just checked, it is currently 80F in there right now. It seems to get some heat down from the attic above it.
I guess this is high for CPU as well, as is to be expected in this case. Currently any real load on the hub will put me in hub mode severe for a few minutes, then it settles down. Hence why I bought the Pro, that I really need to get around to migrating to sooner than later.
Wow, yeah, that doesn’t sound good. If it’s 50+ degrees hotter than its environment, I expect it wouldn’t survive a 110F interior for very long at all. Dang…
Anybody ever opened up a C8? Is it straightforward or do you have to break things? Maybe I could try thermal paste and some heat sinks and drive the temps down for a DIY desert environment…
There’s 4 screws (one under each little pad) on the bottom of the hub. Pretty easy to open, but you’ll void any warranty you might have left. Be careful with the antenna wires.
Maybe a fan that can move the air around the hub would cool it enough?
With No AC, I would expect temperatures in the RV to get much hotter than the outside air temp of 110-120. (Even with fans running on solar) Have you measured the inside temperature while parked?