It would help if you said where you are. But they don't like too much water and that could be what's causing the leaves to yellow and fall.

I live in McAllen, deep south Texas, Rio Grande Valley to be exact, our summers down here are average of 102 F. we don't get much rain either. Hope this helps,and thank you for the feedback. Should i worry that the tree is or might die on me? It's a good 7ft tall, most of the foliage at the top is very green, especially the new branches that have grown out. I scratched the trunk slightly to see if it was green and it sure is, no damage down below.

(I actually replied to this but must have forgotten to hit the "Submit". That's a worry, LOL.) What I had written was that if the foliage up top is green and healthy and the only yellowing is low down or underneath then there's probably no problem. My largest Poinciana is over 15 metres tall (and nearly that across). It always loses leaves and some branches from the bottom. Of course, in the dry season (winter) it loses all its leaves, which is normal as well. Keep an eye on it but I think it will be okay.

Thank you all for your feedback, and I will continue to keep an eye out as well.