Hi, 

This appear to be typical end of season leaf spot to us, probably a fungal leaf spot which is highlighted on the provided link. Many hydrangeas get this, especially the Bigleaf varieties that it looks like you have here. They rarely warrant control especially with the end of the season approaching and leaves about to drop soon anyways. You can make sure to rake up and compost any leaves after they fall to help reduce any spores from overwintering in the soil. 

You can also trim out the dead branches that we can see in the first photo. That was probably some winter dieback which was common on the Bigleaf Hydrangea varieties this year. You can also refer to our pruning guide for hydrangeas since depending on the type, they bloom on new or old wood and you want to make sure you are not pruning off next years blooms. 

Let us know if you have further questions. 

Emily 

Most hydrangeas don't love full sun, especially in the mid-Atlantic region due to our higher summer heat and humidity. Seeing that it is a brick wall behind them too, the sun would be heating up the wall and potentially keep the foliage too hot in the summer. 

Most hydrangea prefer morning sun - enough to get some blooms, and afternoon or at least high mid day shade. Generally having Hydrangea in a North East exposure is usually a good location for them. 

They will probably survive but may require more supplemental water in the periods of high heat or drought, and you may also see crispy scorched leaves in the summer from heat or high sun intensity stress. 

If you wanted to relocate them to a location with more shade, just be sure to water well in advance and you probably want to wait for the high temperatures to pass. They may also go through some transplant shock and drop leaves, or have a little bit of branch dieback but usually within a growing season, they can re-bound. 

you're welcome