White crepe has brown tips on leaves. It is very sick looking. I am in south Texas, bad soil, 100 F. , everyday. It is 5 or 6 years old and 8 or 10 ft. It was beautiful until about 4 weeks ago.
Crepe Myrtle Sick Looking
Certified GKH Gardening Expert
This indicates a watering issue. Either the tree is not getting enough water or there is something affecting the roots that is preventing them from taking up water. In your case, with the extreme temps, the tree likely needs additional watering.