In article , Lil
wrote:

Our hibiscus is planted on a slope in a really sunny area of the yard.
It's been doing fine, despite the almost daily rain--it's been
unusually wet in the S.F. Bay Area, and the water running off from the
neighbor's yard in back. The weather got really hot and dry just
recently, and more and more of the leaves have turned bright canary
yellow. I'm trying to figure out if the hibiscus is dying from lack
of or too much water. Any insight will be greatly appreciated.
Thanks in advance.

If a tropical hibiscus, yellow leaves are common if there are too many
drastic changes. See
http://www.trop-hibiscus.com/q.a.html