One of the advantages of our mild climate is that sod can be installed for much of the year. Even so, the best windows are early fall and spring, when the soil is warm, rain helps with watering, and temperatures aren't stressing the new grass.
Early fall, from late August into October, is often ideal. The ground still holds summer warmth, which helps roots grow quickly, and fall rain takes care of a lot of the watering. A lawn laid in September usually has a solid root system before winter.
Mid-summer installs work but need commitment. New sod laid in July or August has to be watered every day, sometimes twice, until it roots in. Irrigation makes this much easier, and it's worth considering if you're laying a lawn in the dry season.
The one time to wait is when the ground is waterlogged. Working saturated soil compacts it and leaves ruts, and sod laid on mud roots poorly. Whatever the season, the result depends on prep: removing the old lawn, grading for drainage, amending the soil, and rolling it smooth before the first roll goes down.