How does heat damage Avocados? 

California Avocado Commission goes into depth on how avocado trees are effected by heat, but also how you can help aid them from heat-damage. During seasons without extreme heat fluctuations an Avocado Tree gets their water source from the soil through its roots, which moves through the tree into the leave's pores. During the hot summers California usually takes on in early July to mid October, but the temperature definitely varies. The damage creates the fruit to become soft and shrivel up the seed making it no longer viable. 

Learn more about how to Manage your Avocado Trees in the Heat