With temperatures rising, school officials decided to let students go at 10 a.m.
RELATED: Heat causes most weather-related deaths, National Weather Service says
Maintenance crews were called in to assess the problem.
By Tuesday afternoon, officials said the air-conditioning unit had been fixed and the school would be open Wednesday.
Zebulon Middle also closed early because of AC issues. The school's unit has been repaired.
Fuquay Varina High School sustained a "very brief partial outage," according to a Wake Schools spokesperson, and Buckhorn Creek had a partial outage.
All the AC units are back in working order.
Big Weather said the high in Raleigh on Tuesday was 95 degrees.