I'll defer to someone else here who hopefully has some experience with avocados or is at least more familiar with tropical trees if they show up, but I'd still bet on a watering issue. With temps over 100 and watering every four days I wouldn't typically think it's overwatering, but that's really what it looks like in the pics. My surefire way to know when to water potted plants is to get familiar with what the pot should weigh with dry soil and with saturated soil, then a simple lift of the pot can definitively tell you how much water is in there. Besides, most plants recover quickly from underwatering, a wilting plant that hasn't dried out will typically perk right back up with water. Overwatered plants are much harder to recover once they're showing signs of problems.
So, barring anyone else more knowledgeable showing up and saying otherwise... I'd say if you can stick your finger in the soil and feel dampness go ahead and skip watering until the soil dries out a bit then water thoroughly, let the soil dry again, then repeat. If it's not that then you may have a tougher to diagnose and fix problem, like a virus or fungus. If you knew for sure it was overwatering there's all sorts of ways suggested to address that beyond just stopping watering, but I have no experience with them so I can't vouch for any particular method.