The heatwave is expected to affect millions across California and Arizona, with vulnerable populations such as the elderly, children, and those with pre-existing health conditions at heightened risk. Prolonged exposure to extreme heat can lead to serious health issues, including heat exhaustion and heat stroke. Urban areas may experience amplified effects due to heat retention in infrastructure, while air quality alerts in some regions further exacerbate health risks. Residents in areas under extreme heat warnings, such as the Imperial Valley and Coachella Valley, face the highest temperatures, while those in heat advisory zones will still encounter elevated risks.