Hi,
turntable: it can be safely stored, pack it as originaly shipped in all protective meterial, include some silicon gel bags, leave some oil in the bearing and seal it (moisture cannot enter there) apply a very thin film of light oil on any metal (ferrous) part (if any). Carton box may suffer if humidity is high but can be tightly wrapped to protect it even further.
Electronics and speakers: same as above but without oiling anything.
You can cover all inputs and outputs if not plated.
I have kept components in humid areas for over 10 years with no issues.
turntable: it can be safely stored, pack it as originaly shipped in all protective meterial, include some silicon gel bags, leave some oil in the bearing and seal it (moisture cannot enter there) apply a very thin film of light oil on any metal (ferrous) part (if any). Carton box may suffer if humidity is high but can be tightly wrapped to protect it even further.
Electronics and speakers: same as above but without oiling anything.
You can cover all inputs and outputs if not plated.
I have kept components in humid areas for over 10 years with no issues.