An investigation was conducted at Department of Agricultural Meteorology, CCS Haryana Agricultural University Hisar using meteorological data of 60 years (1941-2000) to study the climatic variability and trends in maximum and minimum temperature and rainfall. CERES models were used to determine the impact of future trend scenarios on productivity of wheat and pearl millet in arid zone of Haryana. Annual maximum and minimum temperature showed a decreasing trend during the past 60 years (-0.310C year-1), but in last 30 years have shown an increasing trend (.00870 C year-1). Minimum temperature (annual and seasonal) showed both cooling and warming trend for a long period of 60 years, whereas maximum temperature showed a cooling trend during the same period. On the other hand, rainfall was observed with high coefficient of variability in post-monsoon and monsoon seasons. CERES models were calibrated for crop varieties, wheat (HD 2160) and pearl millet (HHB 67) and then validation was done with use of experimental data of wheat and pearl millet. CERES-Wheat model predicted yield with a variation of -7.3 to 15.3%, whereas CERES-Millet with a variation of -10.9 to 11.3% of the actual yield under different cooling and warming scenarios. Crop results indicated that warm temperature scenarios caused an adverse effect on growth and yield of wheat by hastening the physiological maturity. It was observed that flowering and maturity of wheat and pearl millet crops were advanced and delayed from normal with rise and fall of temperature upto 20 C, respectively.