I leave mine in the jeep probably more than I should in the summer. Hasn't hurt them yet (knock on wood). In a tropical environment, I'd be more worried about the humidity causing corrosion or wiping out the batteries.
Best to go by the manual, especially if it's still under warranty. Like I said, probably more than I should. And now that I mentioned it my battery pack will probably take a dump.
Most detectors mention a maximum and minimum Temperature and a max RH. They error on the low side to prevent warranty claims. To high an RH 90+ can cause condensation with only a little temperature drop. Over heating can cause problems with the electronics. If you see the detector acting or looking funny while at high or low temps or high humidity, get the detector to another cooler /warmer or lower humidity environment. Just use common sense.