  We study the properties of cosmic-ray (CR) driven galactic winds from the
warm interstellar medium using idealized spherically symmetric time-dependent
simulations. The key ingredients in the model are radiative cooling and
CR-streaming-mediated heating of the gas. Cooling and CR heating balance near
the base of the wind, but this equilibrium is thermally unstable, leading to a
multiphase wind with large fluctuations in density and temperature. In most of
our simulations, the heating eventually overwhelms cooling, leading to a rapid
increase in temperature and a thermally-driven wind; the exception to this is
in galaxies with the shallowest potentials, which produce nearly isothermal $T
\approx 10^4$ K winds driven by CR pressure. Many of the time-averaged wind
solutions found here have a remarkable critical point structure, with two
critical points. Scaled to real galaxies, we find mass outflow rates $\dot M$
somewhat larger than the observed star formation rate in low mass galaxies, and
an approximately "energy-like" scaling $\dot M \propto v_{\rm esc}^{-2}$. The
winds accelerate slowly and reach asymptotic wind speeds of only $\sim 0.4
v_{\rm esc}$. The total wind power is $\sim 1\%$ of the power from supernovae,
suggesting inefficient preventive CR feedback for the physical conditions
modeled here. We predict significant spatially extended emission and absorption
lines from $10^4 - 10^{5.5}$ K gas; this may correspond to extraplanar diffuse
ionized gas seen in star-forming galaxies.
