I think a few of us were asking about kid ponchos so I wanted to share my findings.
DS6 is about 45". We got him a Stephen Joseph shark poncho from Amazon. It is 34" x 27". I found that it is just a bit short and the hood is a bit small for his head.
DS4 is 40". We got him a Wildkins poncho from Amazon. LOVE IT! Just the right length and the hood provides really good coverage.
DS2 is 38". We got him a Stephen Joseph tiger. It is great for his small size and he’ll be able to fit into it for a couple more years.