I don't think it is either too much sun or not enuf water - I think what you are looking at is cold damage. Open flowers on any type of bigleaf hydrangea now in the PNW is an indication that the plants are either greenhouse grown or from out of state. And the OP indicates these are NOT greenhouse grown plants. At my nursery, we get a lot of plants from California that are well ahead of our local bloom season - hydrangeas here do not start blooming until the end of June or early July. If they came from out of state, they may have not had sufficient time to become acclimated to our colder climate. And our PNW spring weather has been colder and wetter than normal - a relatively mild frost about a week and half ago nipped all the CA hydrangeas we had on the nursery floor and they ALL have an appearance very similar to the OP's - purplish foliage and crispy flowers and leaves. And while it may be warmer daytime in the WW-Milton-Freewater than it is here in western WA, I'd be willing to bet nighttime temps are still pretty chilly. If it is cold damage, they will come back from that rather easily, although you may need to trim off the damaged portions.

Hi, I have a beautiful old hydrangea, it was here when we moved in 8 years ago and was well established then. Its in a protected spot and has always bloomed beautifully. This year I noticed there was less foliage than usual and there are lots of smallish flower heads instead of the usual large fluffy ones. Now all the flowers are turning brown, but not really dry, they look dirty. I found a couple of leaves that have brown spots that could be anthracnose, but I think I would have expected more leaf damage. Here's a link to some pics. Please let me know if you have any ideas. Thanks! Hydrangea Pics

Aphids, winter damage, leaf curler insects and insecticide/fungicide damage can cause leaves to curl and deform. Search for insects day and night; use an insecticidal soap or spray if you find aphids. If you unfurl the leaves and find insects/worms, you could remove the manually or apply some bt this year and next. Insecticide/fungicide damage requires that someone apply them recently nearby and then the wind spreads them to the hydrangea; the damage can be pruned off.

I agree with previous poster. Once my hydrangea tree starts flowering, its water needs further increase. Mine is 3 years old and did what you described for the first 2 years in times of drought.