The pilot of a Piper PA-24-250 used runway 36 for departure while the windsock was indicating a west wind. The temperature was approximately 83 degrees Fahrenheit, and the pilot noticed a reduced climb performance. After a local flight of approximately 15 minutes, the pilot returned for a full stop landing. He did not recheck the windsock, and elected to use runway 36. During his landing attempt, the pilot noticed that the airplane "wouldn't settle." The pilot considered aborting the landing, but decided against it due to the airplane's position, and the reduced climb performance during the previous takeoff. After touchdown, he retracted the wing flaps in order to obtain maximum braking performance. However, this action also delayed brake application, since the airplane was only equipped with hand-activated brakes. At approximately 30 mph, the pilot steered the airplane off the right side of the runway, in order to avoid running off the end and incurring more severe damage. The airplane continued down an embankment, and was stopped by underbrush and trees approximately 250 feet beyond the runway. According to an eyewitness, the airplane touched down on the last third of the runway, and the wind was from the south at the time of the event.