The present investigation was carried out at research farm of Tirhut College of Agriculture, Dholi, Muzaffarpur, Bihar during Rabi 2017-18. The larval population was initially recorded in 7th standard week (third week of February) (2.33 larva/plant) with a peak in 13th standard week (2nd week of April) (5.33 larva/plant). Mean larval population of Helicoverpa armigera on chickpea variety KPG-59 was found positively correlated with maximum temperature (0.495), whereas minimum temperature and relative humidity (7 Hrs and 14 Hrs) shows negative and non-significant correlation (-0.055), (-0.553), respectively. Correlation between rainfall and larval population was found negative and significant (-0.666). However, all the weather parameters together contributed 80.7 percent towards Helicoverpa armigera larval population.