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Ambri apple is an important temperate fruit crop of Jammu and Kashmir, but locally selected genotypes may differ in their phenological timing and thermal requirements. The study aimed to evaluate the phenology of these selections based on their thermal responses. The present investigation was conducted at the experimental field of Krishi Vigyan Kendra, Ganderbal, during 2023. The experiment comprised seven Ambri apple selections, namely GA-AS-01, GA-AS-02, GA-AS-03, GA-AS-04, GA-AS-05, GA-AS-06 and GA-AS-07. The experiment was laid out in a Randomised Complete Block Design (RCBD) with three replications. Statistical analysis revealed significant differences among the Ambri apple selections for the recorded observations. GA-AS-04 required the maximum number of days (225.00) and accumulated the highest Growing degree days (GDD) (3161.80 ^oC days), Photothermal unit (PTU) (42587.59 ^oC days), Heliothermal unit (HTU) (23277.64 ^oC days) and Hydrothermal unit (HYTU) (220521.10 ^oC days %) to reach maturity. Conversely, GA-AS-02 required the minimum number of days (215.00), GDD (3036.57 ^oC days), PTU (41112.04 ^oC days), HTU (22335.29 ^oC days) and HYTU (211827.50 ^oC days %) to reach maturity. Heat use efficiency (HUE), photothermal use efficiency (PTUE), heliothermal use efficiency (HTUE) and hydrothermal use efficiency (HYTUE) were reported to be highest in GA-AS-05 (8.22, 0.60, 1.11 kg ha^{-1 o}C day^-1 and 0.11 kg ha^{-1 o}C day^-1 %, respectively) and lowest in GA-AS-07 (6.82, 0.50, 0.92 kg ha^{-1 o}C day^-1 and 0.09 kg ha^{-1 o}C day^-1 %, respectively).