Check out this care sheet. Is very accurate.
I would add to keep an eye open for respiratory infections. With fluctuations in temperature viral infections can catch on. If you see little bubbles on their nose when they breath, they could have one. Viral infections usually resolve on their own, but if they are weak it could complicate into bacterial pneumonia. If you see bubbles make sure you take them to a vet. If you don't have one that doesn't see reptiles, you can have them weigh the turtle and give you a prescription. They probably have antibiotics. The one of choice is called Baytril, at 7.5-10 mg/kg diluted with normal saline Intramuscular if diluted with saline. They can teach you how to inject them. I hope you don't need this information but is good to have.