Are having temper tantrums as 13yo boy normal?

NO,of course not: Temper tantrums are a function of the more primitive part of the brain. This is made to be much more reactive by high calorie malnutritiond, particularly all the sugary stuff and even sweeteners. Look to diet as the cause and see my blog "oxygen, the spark of life".

A 2-year-old type : tantrum is not an age-appropriate coping skill at 13. Get info from school on issues with behavior, academics & peer interaction. Record immediate antecedent of the behavior, behavior (hitting, kicking, yelling, crying) & immediate consequence ( your response) to the behavior for pediatrician to review for referral to a developmental/ behavioral pediatrician or child psychiatrist & psychologist.