LOSS OF ACFT CTL ON TKOF.

Narrative

PVT PLT (2 WKS) LOST DIRECTIONAL STABILITY ON TKOF AND TRAVELED ACROSS GRASS AREA BTWN TXWY AND RWY. CAUSE: CHANGE IN WX FROM VERY HOT (100 PLUS DEGS) HIGH HUMIDITY AND CHANGE IN WT ON BOARD TO VERY LIGHT. WX ON DAY OF INCIDENT WAS COOL (76 DEGS) AND LOWER HUMIDITY. PLT WAS NOT PREPARED FOR SUCH AN EARLY ROTATION -- PLANE WANTED TO FLY TOO SOON. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SAYS SHE; 'WORKED INTENSELY HARD ALL SUMMER TO PASS THE PVT PLT EXAMINATION AND CHK RIDE.' DURING THAT TIME HIGH TEMP AND HUMIDITY SET A HABIT PATTERN IN RPTR'S MIND AS TO THE ACFT ROTATION POINT. ON THIS TKOF; AND HAVING JUST BEEN SOLOED FOR PVT LICENSE; THE RPTR SAYS SHE WAS VERY NERVOUS. THE WX PATTERN HAD CHANGED TO COOLER; DRIER AND A 6-7 KT HEADWIND. CONSEQUENTLY; RPTR SAYS SHE WAS UNPREPARED FOR THE ACFT WANTING TO FLY SO EARLY IN THE TKOF ROLL. IT CAME OFF THE GND A FEW FEET AND RPTR HAD DIFFICULTY CTLING IT; SO FORCED IT BACK ON TO THE GND; BUT RAN OFF THE L SIDE OF THE RWY AND CAME TO REST IN THE GRASS. NO ACFT OR PROPERTY DAMAGE; BUT ARPT MGR CALLED THE FAA; WHO; WHEN HEARING THERE WAS NO ACFT DAMAGE OR INJURIES; RELEASED THE ACFT TO THE ARPT MGR.