SR22 pilot reported the aircraft had an unusual vibration during engine start and takeoff roll. Pilot rejected takeoff and later found a partially detached decal on the spinner may have caused the vibration.

Narrative

On Day 0; at approximately XA30; Aircraft X attempted departure from ZZZ to ZZZ1. Both departure and destination airports presented challenges; including high density altitude; elevated temperatures; strong winds; rain; and potential icing conditions enroute. Additionally; logistical concerns at ZZZ1--including closed FBO services and limited ground transport--added to the operational complexity.Comprehensive preflight planning was conducted; with weight and balance verified within limits and climb performance assessed as acceptable; albeit on the high side. Following engine start; temperatures--particularly CHTs and oil temperatures--rose rapidly due to strong tailwinds that impeded proper engine cooling. Though within limits; the temperatures were higher than typically observed.Shortly after; an unusual vibration-like noise emerged. Turning the aircraft into the wind reduced engine temperatures; stabilized oil pressure; and eliminated the noise. As a precautionary measure; the crew shut down the aircraft and conducted a thorough inspection of the engine and propeller area. No visible issues were found; and engine indications remained normal.Upon restarting; no vibration or abnormal noise was noted during taxi or runup. Confident that the aircraft was airworthy; the crew prepared for departure. However; during the takeoff roll; the unusual vibration reappeared. With cumulative risk factors--including high density altitude; weather; and now a persistent but unconfirmed anomaly--the decision was made to abort the takeoff. ATC was promptly advised; and the aircraft exited the runway safely.Recognizing that troubleshooting at night in windy conditions would be challenging; the crew secured the aircraft overnight. The next morning; a detailed inspection revealed no mechanical anomalies except for a partially detached decal on the spinner; determined to be the likely source of the vibration noise. Subsequent engine start; runup; and departure were conducted without incident; and the mission was completed under improved weather conditions with reduced risk.