American Journal of Climate Change, 2014, 3, 306-325 Published Online September 2014 in SciRes. http://www.scirp.org/journal/ajcc http://dx.doi.org/10.4236/ajcc.2014.33028 How to cite this paper: Romero-Higareda, C.E., et al. (2014) Temperature Trend Analysis in the North Pacific Watershed in Mexico. American Journal of Climate Change, 3, 306-325. http://dx.doi.org/10.4236/ajcc.2014.33028 Temperature Trend Analysis in the North Pacific Watershed in Mexico César Enrique Romero-Higareda, Luz Isela Peinado-Guevara, Samuel Campista-León, Juana Cázarez-Martínez, Jorge Guillermo Sánchez-Zazueta, Rogelio Sánchez-Bañuelos Unidad Académica Escuela de Biología, Universidad Autónoma de Sinaloa, Culiacán, México Email: cesar_romero_47@uas.edu.mx Received 15 June 2014; revised 12 July 2014; accepted 5 August 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Through the monthly data of 71 meteorological stations of the North Pacific Watershed in north- west Mexico, the annual trends of nine temperature variables were estimated using the non-pa- rametric Mann-Kendall test and the Q Sen’s slope estimator. Annual Q Sen’s slopes were analyzed in spatial terms using geographic variables as independent factors and likewise with Moran’s I index. Three major physiographic zones were used to perform a regional analysis using pooled data. The monthly trends were also analyzed. Divergent annual trends were found for the nine proposed variables and warming trends were predominant in almost all of them. Latitude is the most relevant factor in the spatial distribution of the Q Sen’s slopes. Four temperature variables were found statistically clustered, as depicted by the Moran’s I index. The largest regional Q Sen’s slopes values were found in the Coastal Plains. In this area a larger increase in minimum tempera- tures was observed, in contrast with the Sierra Madre regions, where the largest rate of increasing change was found in maximum temperatures. The monthly analysis indicates warming trends in the first six months of the year with a sudden decrease in July and also a noticeable decrease in the slope values in December. Keywords Climate Change, Northwest Mexico, Regional Analysis 1. Introduction Inside the frame of climate change, mainly attributed to anthropogenic activities such as the emissions of green house gases and soil cover change [1], divergent temperature trends have been documented at different spatial and temporal scales. Evidence of the effects of human activities on climate systems have been described by modeling programs [2] [3] who predicted an increase in temperature associated to change in soil cover, essen-