acccording to wat i know, storing negatives in dry cabinet will cause them to detoriate faster due to the high temperature. its better to store negative in a cooler place. to minimize humility, u can wrap them up with newspaper or sore in some air tight container with silica gel.
but i think the more crucial ones are the negatives sleeves. they are the ones that are in direct contact with the negatives. most sold in singapore are not archival. i am not very sure about it. maybe u can try asking fotoguide, cathay and ruby.
actually, i am not very sure abt wat is high temperature. but i heard from other photographers that they keep their negatives in an air-conditioned room which is on for 24 hrs....think my dry cabinent with a temp of 28 degrees isn't that suitable too.