When leaves turn yellow it generally has something to do with water. The leaves will turn yellow with too much water or not enough. With your plant I suspect not enough. I have found during the growing season Adenium obesum are thirsty. Much more than other succulents. I live in California which my climate is much different than yours. We get zero rain from May-Oct. So it’ll be 100+F with the humidity at like 27% during the hottest days. I think the hottest day I saw last summer was 115F. The moisture just gets sucked outta everything. Keep that in mind, but I can water my Adeniums three x‘s a week. Probably could get away with 4x a week during the hottest and driest days. I also have mine in a mix of about 50% pumice, 20% perlite, and 30% cactus mix. So my mix is fairly gritty and dries out fast. I know I just told you they like lots of water while they’re growing so why don’t I take out the grit. No succulent likes to have constant wet feet, and the grit allows the mix to dry out fast so I can frequently flush the roots with clean fresh water.

This is what I would suggest or what I would do🙂. Your soil should be amended with at least 50% perlite or pumice. Side note there’s a woman on YouTube that is the queen at growing Adeniums and she lives in Florida. Here’s her channel. It’s interesting she uses bark as her grit. I definitely suggest checking her out especially since she’s from your state.

Thank you so much for all of the advice, Kara!!!