This is a great period of weather for transplants...cool, cloudy. I've never lost a transplant when we have weather like this. A good shot in the arm will be taking some of the Miracle-Gro water soluble tomato fertilizer (yes this, not the blue stuff) and watering your transplants with this mix in about a week. It has a lower nitrogen content so it will help promote root and stem health. One good application should do, and that will bolster the plant(s) before the hot weather comes in.