I have loved and grown rhodies for decades... both in the NE and the Pacific NW.
Fanciers and gardeners have told me that rhodies curl their leaves in the cold partly to stop transpiration from the under surfaces of the leaves.... because cold air doesn't carry as much moisture and they cannot replace moisture lost without some warmth. So yes. They are very accurate thermometers as their lives depend on maintaining their moisture.
I have loved and grown rhodies for decades... both in the NE and the Pacific NW.
Fanciers and gardeners have told me that rhodies curl their leaves in the cold partly to stop transpiration from the under surfaces of the leaves.... because cold air doesn't carry as much moisture and they cannot replace moisture lost without some warmth. So yes. They are very accurate thermometers as their lives depend on maintaining their moisture.