The cabbage butterfly, Pieris brassicae L. (Lepidoptera: Pyeridae), is a major pest of kale (Brassica oleracea, Brassicales: Brassicaceae) and oilseed rape (Brassica napus, Brassicales: Brassicaceae) in temperate regions, including the cold arid areas of Ladakh, India. Temperature critically influences its development and survival, yet comprehensive thermal thresholds for predicting its phenology under field conditions remain poorly characterized. Here, we investigated temperature-dependent development and survival across all life stages of P. brassicae under controlled conditions. Eggs, larvae, and pupae were reared at five constant temperatures (20, 25, 30, 35, and 40 degrees C), with survival rates, developmental times, and developmental rates recorded for each stage. Egg hatchability and adult survival were highest at 35 degrees C (90.5% and 80.2%, respectively), while larval and pupal survival peaked at 25 degrees C (88.1% and 85.1%, respectively). Developmental rates increased with temperature, with eggs developing most rapidly at higher temperatures. Using linear regression, we calculated lower developmental thresholds (LDT) of 10.41 degrees C for eggs, 5.00 degrees C for larvae, and 7.77 degrees C for pupae. The corresponding thermal constants (K) were 68.49, 833.33, and 277.77 degrees-days for eggs, larvae, and pupa, respectively, with a total requirement of 1179.59 degrees-days from egg to adult. Field monitoring in Kashmir Valley revealed that P. brassicae adults first emerged on Julian day 97 (April 7), with approximately 4.5 generations occurring annually. These findings provide essential thermal parameters for developing predictive models to support timely pest management interventions in Brassica oleracea (kale) and Brasica napus (oilseed rape) cultivation under changing climatic conditions.