FYI, ASHRAE (American Society of Heating, Refrigeration, and Air-conditioning Engineers) has released new guidelines for temperature and humidity conditions for IT equipment. Among the changes (see p.8), are new classes A3 and A4, which allow 5C-40C and 5C-45C temperatures in data centers (respectively), along with 8-85 and 8-90% RH.
There are even guidelines for lower humidity level if certain procedures are followed.
P.S. Thanks to Pasi Vaananen for the heads-up.