Simulated difference in the mean annual number of days with a minimum temperature less than 32F (Tmin < 32F) for the Southwest region, for the 2041-2070 time period with respect to the reference period of 1980-2000 (top). Color with hatching (category 3) indicates that more than 50% of the models show a statistically significant change in the number of days, and more than 67% agree on the sign of the change (see text). Mean annual number of days with Tmin < 32F for the 1980-2000 reference period (bottom left). Simulated mean annual number of days with Tmin < 32F for the 2041-2070 future time period (bottom right). These are multi-model means from 8 NARCCAP regional climate simulations for the high (A2) emissions scenario. Changes are downward everywhere. Decreases are largest in high elevation areas and smallest along the coast, as well as southern California and Arizona.