A study was conducted in the state of Arunachal Pradesh in order to study on the climate change pattern in Arunachal Pradesh for the time period 1987 to 2018 and its impact on the production and productivity on rice (Oryza sativa L.) and maize (Zea mays L.) in the state. The study was carried out in two districts of Arunachal Pradesh, viz. East Siang and Lohit; each being the highest producing district of rice and maize in the state respectively. The study showed a declining annual rainfall pattern in the study area. The monthly rainfall pattern and seasonal rainfall pattern exhibited erratic rainfall pattern with a non uniform linear trend for different months and different seasons. The districts of East Siang as well as Lohit received a minimum monthly rainfall of 0.00 mm while the highest monthly rainfall was recorded to be 2363 mm in the month of August for East Siang and 786.70 mm in the month of April for Lohit district. Both the districts received maximum seasonal rainfall during the monsoon months of April to September with 5992.90 mm and 2831.1mm of rainfall received in East Siang and Lohit districts respectively. The study did not show a significant change in the annual rainfall pattern. However, the monthly and seasonal rainfall exhibited a high inter-year variation and irregular trends proving that the study area observed erratic monthly and seasonal rainfall during the study period. The productivity of rice and maize crops were found to have decreased by the end of the study period. It was also found that total annual rainfall had a significant effect on the yield of paddy but not in maize.