Are those the times when that area gets sun now or in the summer?

It's in the summer since in Connecticut it's still winter. Right now they get a lot of sun since the trees are bare. :)

It is hard to say coming from Texas. Over here, the hydrangea leaves would suffer from sunscorch and they would bleach out and turn either white-ish or yellowish. For that reason, your plan would be a bad idea **here**.

But... you are not in Texas so I will mention that several relatives in Mass are growing Nikko Blue -with no problems-on the west-facing side of the house. I am not sure exactly when they start getting sun in the summer but it would be sometime after 1pm. Pine trees then provide shade about 1 hour before sundown (this is in the summer time). The plants have done fine throughout the years and the blooms have not been affected (sometimes blooms will brown out if exposed to too much sun).

Because the sun exposure is different in the northern half of the country versus the southern half of the country, you might be able to do plant them successfully. Some rhodies, for example, can be grown in full sun over there but must have shade here by 11am.

Look around for an existing plant being grown under similar conditions so you can observe what happens or even ask the owner. Or experiment to confirm if you can. Try just one plant for starters. If you can, grow it in a pot for one year so you can easily move it elsewhere if the sun becomes a problem or if the blooms turn brownish early in the summer. A good and constant supply of moisture can help grow hydrangeas where it is a little bit sunnier than normal. Water when the soil feels 'almost dry' or dry to a depth of 4". Wet soil will promote root rot so just keep the soil moist. And mulch them well too.