Vulnerability to heat hazards is on the rise in cities. Heat hazards appear at the intersection of seasonally hot climates, summer heat waves, and sity-specific urban heat islands, and are exacerbated by localized climate change effects. Urban heat waves linked to global and regional climate change have been shown to have inceased in frequency and intensity over the 20th century as high temperatures exceed normal ranges of temperature variability. Among weather-related hazards, extreme heat accounts for the majority of fatalities in the United States. Extreme heat is a seasonal phenomenon, with prolonged events occurring during summers, and intra-urban exposure varying according to ecological and built environment structure.