The heatwave poses significant health risks, particularly for vulnerable populations such as the elderly, children, and those with pre-existing health conditions. Extreme heat warnings are in effect along the coast from Santa Barbara to San Diego through Thursday. Overnight temperatures in cities like Los Angeles and San Diego are expected to remain in the mid to upper 70s°F (24-26°C), offering little relief. Residents are advised to limit outdoor activities, stay hydrated, and take precautions to avoid heat-related illnesses.