Columbus Mayor Michael Coleman says four fire hydrants will be opened from 1 p.m. to 4 p.m. today and Friday to help keep residents cool in the sweltering heat. City workers will supervise the use of the hydrants on North Ohio Avenue, Rhodes Avenue, Briarwood Avenue, and at the corner of Wicklow and South Hampton streets. Coleman notes air-conditioned recreation centers are open from 9 a.m. to 6 p.m. weekdays and Seven city swimming pools are open. Meterologist Rob Carolan says Columbus will see a high temperature near 101 degrees today. A heat advisory is in effect until 8 p.m., and health officials urge people to stay inside and drink lots of water if going out of doors.