PHILADELPHIA (AP) — Students in the Philadelphia School District will be going home early for the third day in a row Thursday.

The district announced Wednesday that all schools will dismiss students at 1 p.m. Thursday due to continuing hot conditions. All after-school activities scheduled Thursday including all athletic programs and professional development sessions are canceled.

Officials said as heat builds during the day, "buildings are experiencing uncomfortable conditions" — and because temperatures remain high into the evening, many buildings don't cool overnight. Only 27 percent of the district's school buildings have central air conditioning.

The National Weather Service says a high near 90 is expected Thursday for the city but humid conditions will push the heat index into or near the mid-90s.