Thank you for your feedback.
For my mental health, I decide I will pick my last apples when temp is around 25-26 F.
Last Thurs morning, temp was at 26F with hard frost. Ice/frost covered everything. Fortunately, my GR apples were in bags so they got protection.
Fri morning was at 23F, quite dry, no frost. I should have left an apple or two to test the temp.
I’d like to be able to store my apples so I won’t wait until it is in a low 20’s.