You need some super fine merino base wear. I live in a warm climate but which is really cold from about mid June to mid August - frosts etc.
This merino is fantastic.
here is a link where you can buy them online and it will be posted to you. The icebreaker gear can be ordered online in the US. [www.icebreaker.com]
Wild South is also good. I got this top for my son for Christmas. [www.wildsouthclothing.co.nz] He has just spent a month in Europe and only took this top off to wash.
Kathmandu is in both Australia and New Zealand. It also has an online store. Its the merino you want, not the synthetics [www.kathmandu.com.au]
Because it is summer downunder, you might find some good stuff at sale price.