Changes in the Frequency of Different Categories of Temperature Extremes in India

Abstract In the context of climate change and its impact on sectors like agriculture and health, it is important to examine the changes in the characteristics of temperature extremes of different intensities and duration. In this study, an India Meteorological Department gridded temperature dataset is used to examine the changes in the frequency of occurrence of extreme temperatures over India and its seven homogeneous regions during the period 1969–2005. Results indicate a significant decrease in the frequency of occurrence of cold nights in the winter months in India and in its homogeneous regions in the north except in the western Himalaya. Southern regions show a drastic decrease in the frequency of cold nights relative to the period 1969–75. A significant increasing trend in the number of warm days in summer is noticed only in the interior peninsula. In the entire country and on the east coast and west coast, the maximum number of warm days in summer has been noticed only during the last decade, 1996–2005. Further, in the whole country the maximum number of intense warm days and nights in summer has been observed in the last decade. A significant increase in the number of cold days in winter is observed in the north-central and northeast regions. Changes in the frequency of warm and cold exceedances indicate maximum warming in the west coast as compared with all other regions. In sum, such spatial and temporal changes in the characteristics of all categories of temperature extremes broadly suggest warming trends in large parts of India.