Is Moleskin warm?
Moleskin is surprisingly comfortable in a wide range of temperatures. The densely woven weft-face fabric makes it nearly windproof, making it a great fall and winter option. It is not uncommon to be comfortable on a 30-40 degree F day in just a Moleskin shirt. A heavyweight grade, such as the M1A, might even be warm enough for below 30.
However, the high air permeability of the 100% cotton keeps the garment pleasantly cool in warmer conditions. You can easily walk to work on a crisp 30-40 degree November morning, work comfortably in an office, and walk home as the sun falls and never have to add or shed a layer.