David Kelly sent his son to school at Parkwood Academy, in Shirecliffe, wearing shorts as England saw its highest temperatures of the year on Monday, with thermometers hitting the high 20s.
But he was left angry, and said the school sent the youngster home for breaking the school dress code, which includes long trousers. He says his boy was one of seven told to go home.
The school says he withdrew his son over the row.
Mr Kelly says some schools have allowed pupils to wear their school PE kit instead of their regular uniforms during the heat, and was not happy that Parkwood were not allowing that sort of flexibility.
He said: “My child goes to Parkwood school in Shirecliffe. All other schools in the area are allowing students to wear their uniform specification PE kit due to the heat. Parkwood are refusing to allow this – they want students to wear full uniform. All other schools in the area are allowing pupils to wear heat appropriate clothing.
“My child and a further six have already been sent home for not wearing full uniform.”
He said in the past the school had also refused to allow his son to drink from a fizzy drinks bottle which had been filled with water, and his had in the past been emptied in front of him.
The school said in a statement that it had high expectations on uniform, but had relaxed rules on blazers during the heatwave.
A spokesperson for E-ACT Parkwood Academy said: “We have high expectations when it comes to uniform, but of course during these high temperatures, we do not expect students to wear blazers.
“Keeping hydrated is also very important and whilst we would normally not allow students to drink from plastic bottles, they are allowed to drink water from bottles in this heat.”
This week has seen temperatures soaring across Sheffield, with temperatures having reached the upper 20s at the start of the week.
Temperatures are due to increase again at the start of next week, with the Met Office forecasting the mercury will rise beyond 30C next week.