Power system planning and operations are significantly affected by the air temperature patterns within a geographic region. Climate non-stationarity, including more severe heat waves, thus presents new challenges for maintaining reliable infrastructure operations. This is especially risky in the U.S. Southwest because the region heavily uses electric air conditioning and thermal power generation technologies - who's electrical performance varies with air temperature. Using structural equation modelling (SEM) techniques, we considered how unprecedented high air temperatures could result in insufficient electricity generation resources to meet peak electricity demand for Phoenix (exporter) and Los Angeles (importer) regions. If the two regions reach 44-58°C (111-136°F) at the same time, then they could experience a net power deficit. Since significant population growth is expected in both regions, different urban planning approaches are discussed for proactive governance to maintain reliable power infrastructure considering trade-offs in economic, social, and natural resources for different stakeholder groups.