It is hard to answer without knowing which hydrangea you are talking about. For example, Macrophyllas' leaves are quite sensitive to the summer sun so they suffer when exposed to afternoon sun. Now, for example, they may be fine with full sun. In July, it is another story.

The amount of soil moisture provided can also help the leaves but, this is a risky game that requires well draining soil because too much water and you could get root rot..

It also depeneds on how strong your sun is during the summer months. One of my Macs once was suddely exposed to lots of afternoon sun when a thunderstorm damaged parts of a Crape Myrtle that shaded the hydrangea. Then it took 1-2 weeks for the leaves to scorch. However, my MIL had a Nikko Blue in afternoon sun exposure up in the Northeast with no issues (the sun is "weaker" over there).

For best performance in sunny areas, consider paniculatas and maybe oakleaf hydrangeas. Geographical location and extra soil moisture can help some Macs in sunny areas. If you want to experiment, consider planting one in the location you are considering but plant it in the plastic container that it came in. Meaning did a hole and plant the pot and all there:

... cover the sides of the pot with soil and mulch the top as usual. Water as usual for that area, or more if you see problems. Then if the leaves suffer from sun scorch during the summer months, pull the pot out and move it to a better location.

Luis

Thanks for the suggestion! I bought two big leaf hydrangea, beautiful pink mop heads. I actually just bought a larger pot to plant them in and hope to try your scenario of seeing how they do with different sun exposure. I then can move them if necessary.

Thank you!