The impact of climate change on annual air temperature and precipitation has received a great deal of attention by scholars worldwide. Many studies have been conducted to illustrate that changes in annual temperature and precipitation are becoming evident on a global scale. This study focuses on detecting trends in annual temperature and precipitation for the nine states in the Northeastern United States. For this study, the widely used modified Mann-Kendall test was run at 5% significance level on time series data for each of the nine states for the time period, 1900 to 2011. The resultant Mann- Kendall test statistic (S) indicates how strong the trend in temperature and precipitation is and whether it is increasing or decreasing. For temperature, all the states indicate statistically significant increasing trends, except for Pennsylvania and Maine that do not indicate statistically significant trends. In the case of precipitation, the states of New Hampshire and Maine do not show statistically significant results, while the other states show statistically significant increasing trends. On the contrary, linear trend line plotting indicates increasing trend in temperature for all nine northeastern states in the range of 0.00006 to 0.02 °F/yr, while a US EPA study demonstrates that the US average temperature rise is 1.3°F/century. [1] For precipitation, the linear trend line indicates a decreasing trend for Maine, while the other eight states have an increasing trend that ranges from 0.03 to 0.13 mm/yr.