In very hot dry summers you may have to protect your plants from burning and drying out. Plants do have systems that help them adjust to hot and dry weather conditions. For example they close off heir stomata to prevent evaporation but never the less they occasionally will need help.
Some plants can only take so much sun and get burned and dry if left unprotected for long periods without rain and in high temperatures for long periods without relief.
Check a plants location. Does it receive direct sunlight for extended periods. Does it need shade. Create shade for your plants if they