In summer time, you need to prevent sun damage and keep the hair moisturized. You can wear a hat or a silk scarf to protect your hair, or you can use a sunscreen hair conditioner.
Minimize using hair dryers or curling irons, as they can make the hair dry. When washing or rinsing the hair, be sure to use lukewarm water or cool water, but not hot water. Use a moisturizing shampoo, as it helps to keep the hair moist.
Drinking plenty water is also important, as this helps you keep hydrated and improves your overall health. Some hair care products contain formaldehyde or alcohol, they tend to make hair dry - try using some natural or milder products.