Because of recent high heat and humidity, district leaders considered letting students out early on Thursday and Friday but decided to have classes go all day.

About half of the district's 55 schools don't have air conditioning. In June 2006, voters approved a bond issue to install air conditioning at 18 more schools over the next three years or so.

District officials urge students to wear light weight, light colored clothing and bring along water bottles. High temperatures likely will be in the low 90s on Thursday and Friday and, with humidity, it will feel like the high 90s.