Try "blessings"
I was looking for the very same thing. It is very easy to use and offers tools for coloring, styling and positioning in the terminal. What you need is as easy as:
from blessings import Terminal
t = Terminal()
w = t.width
h = t.height
Works like a charm in Linux. (I'm not sure about MacOSX and Windows)
Download and documentation here
or you can install it with pip:
pip install blessings