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346 assessment of climate change in the southwest united statesas 6°F to 7°F (3°C -4°C) during the mid-century, with areas of especially high increasesconcentrated in the western Sonoran Desert (Montero and Pérez-López 2010) and thenorthern Chihuahuan Desert (see Chapter 6, Figures 6.1 and 6.8). viiiAssociated with the maximum and minimum temperature projections are an arrayof projections for derived parameters and temperature extremes (Table 16.1). Some keyderived and extreme temperature projections include large projected increases in coolingdegree days in Southern California and Arizona (up to 100 degree days, using a 65°F(18°C) baseline; see Chapter 6), large increases in the annual number of days with maximumtemperatures greater than 100°F (38°C), including increases of more than 30 to 35days in the central Arizona and northwest Chihuahua border regions (see Chapter 6 andFigure 16.2), increased heat wave magnitude (but with more humidity, therefore havinga larger impact on nighttime minimum temperatures; see Chapter 7), ix and diminished xfrequency of cold episodes (see Chapter 7).Figure 16.2 Change in the number of days with a maximum temperature greater than100°F (38°C). The top map shows the change between the NARCCAP (Mearns et al. 2009) multimodelaverage for 1971–2000 (lower left) and the average for 2041–2070 (lower right). Map generatedby Laura Stevens.