It’s known from other studies comparing rural and urban temperature changes, including in Arizona, that urban temperature increases are generally larger than in rural areas, Garfin said.

Climate change and the heat island effect make it less comfortable and less safe for outdoor work, he said.

“There are effects on evaporation and evapotranspiration, effects on energy bills for summer cooling, and additional wear and tear to the built environment materials that are affected by heat, such as roadways,” he said.

Statistics bear out the greater impact of the heat island effect, said Arizona state climatologist Nancy Selover.

When comparing the Phoenix area’s average annual low temperature from the period 1941-70 to that of the period 1991-2018, she found a difference in the range of 7 to 9 degrees, Selover said. The difference in average annual high temperatures between those two periods was 2.3 degrees, by contrast.

Since minimum temperatures typically reflect heat island impacts, that’s why she believes the heat island effect was more significant, Selover said. She doesn’t have similar comparisons for Tucson but believes the two cities have similar patterns.