Temperature mapping is a key asset in supporting the clinician during thermal ablation (TA) treatment of tumors without adding additional risk to the TA procedure. Herein we report our experiments on multidimensional thermal mapping during radio frequency (RF) thermal ablation treatments of an ex-vivo animal organ. The temperature was monitored using several arrays of fiber Bragg gratings properly positioned around the RF applicator. The results show the effectiveness of our proposed method at assessing the TA probe depth and demonstrating how the insertion depth directly influences the maximum temperature and the treated area of the radio frequency ablation.