Adding a mulch has its advantages in any kind of climate. In colder periods it insulates the soil during the winter months and in warmer periods it stops the soil from drying out by sealing in the moisture. It keeps weeds at bay by blocking out the light and any that do get a hold are easily removed 'cause they're rooted in the loose mulch.
All kinds of invertebrates, fungi and bacteria live and feed in the mulch slowly releasing nutrients creating a balanced ecosystem and adding to the survival of your plants. Plus, any organic mulch will with the help of those organisms improve the soil over time as an added bonus.
