Looks just like insufficient watering. Seattle may not get too hot (except for this week) but a full-on southern exposure can generate some pretty warm soil temperatures in a container and they dry out quickly. I water mine on pretty much a daily basis. You want to keep the soil consistantly moist - not wet but not allowed to dry out either. The white spots are most likley powdery mildew and that very commonly occurs when soils are allowed to dry too much (as compared to humidity/air moisture).

Personally, I'd cut the plant back. Less topgrowth to hydrate will help it recover quickly and I'd also consider planting in the ground this fall.

And as long as you keep watering, it's not going to die :-)

Agreed though that bloom looks like C.florida sieboldii not Cezanne and I've killed three of them in Portland....

Thank you both for your thoughts. I will water and cut back and then plant it in the ground. The bloom is about 2.5 months old and refuses to drop and is very faded which is why it probably looks like C.florida sieboldii :)

Hopefully it will make it through, thanks so much!

FWIW ~ it will not die they are hardier than they look when they go thru heat reaction I believe. Agree w/ expertise of gardengal148!

My Cezanne had 1 similar summer experience (even completely crunchy dry) but recovered w/ waterings & came back as beautiful as ever also my Cezanne had yellow antlers. BTW I noticed some mottling foliage are those heat-stroke symptoms & not chlorosis?

Chlorosis isn't mottling. It is when the veins stay green but the rest of the leaf turns yellow.

Here is a link that might be useful: images of chlorosis