  We discuss thermodynamics of fuzzy spheres in a matrix model on a pp-wave
background. The exact free energy in the fuzzy sphere vacuum is computed in the
\mu -> \infty limit for an arbitrary matrix size N. The trivial vacuum
dominates the fuzzy sphere vacuum at low temperature while the fuzzy sphere
vacuum is more stable than the trivial vacuum at sufficiently high temperature.
Our result supports that the fluctuations around the trivial vacuum would
condense to form an irreducible fuzzy sphere above a certain temperature.
