Cold Weather, Hot Weather

Nope, just how hard or easy the ground is to dig.

Yes and no. High temperatures will heat up the ground, which should be a concern for you if you're detecting in mineralised soil, because you'll notice the detector becomes more 'chattery'. You can fix this by ground balancing the detector, so it adjusts to the soil. If you don't ground balance, the depth of the detector doesn't *decrease*, but you may confuse deep targets with mineralisation messing with your detector.

Especially if you're gold prospecting in hot, mineralised ground, you want the machine to be ground balanced as best as possible so you can hear those faint whispers which might be small gold nuggets.

I bet it could make a tiny difference between -20 and 120 just because most metals will conduct differently at temperature extremes. I think moisture has more to do with depth than anything else.

I can't say I have been able tell any noticeable difference in depth.
Ground mineralization and the moisture content of the soil are what I have noticed make a difference.

Aka metal detectors points out which coil is PTS and which are not.
All the AKA coils produced before 15th of March, 2013 tend to have GB (Ground Balance) temperature drift caused by great temperature change. Drifted GB means the possibility of false signals can exist.All the AKA coils produced after 15th of March, 2013 are done with PTS technology. This technology significantly reduces GB drift even if temperature changes from -13 degrees fahrenheit to 77 degrees.If you have a Whites VX3 or DFX or 3vi, then you would most likely be experiencing possible false signals with more extreme temperature changes. Maybe I should say with whatever ground balancing system your machine uses, temperature change can possibly effect it or whether it is not a concern for your application.