Black Cherry...Slow to ripen??

[jerseyjohn61]

I have a BC in a container on a HOT 2nd story
balcony(brick back wall). It's a healthy rascal
that has grown well despite its' late start.
Has about 60 fruits on it.

About 6 of the fruits have been full size for
nearly 3 weeks and show no sign of blushing.

Is this normal or prehaps a result of the heating
of the day as well as the residual heating at night?
Balcony has a great southeastern exsposure
with 8 + a day of sun.

Thanks....jj61