London is grappling with significant heat challenges, primarily due to the urban heat island effect, which results from extensive dark surfaces like concrete that absorb heat. This phenomenon makes London the hottest city in the UK, often several degrees warmer than its rural counterparts. The city's infrastructure is poorly equipped to handle high temperatures, leading to overheating in homes and offices, which negatively impacts productivity and poses health risks, especially for individuals with pre-existing conditions. Tragically, heatwaves have resulted in hundreds of deaths each summer. To adapt, London must adopt strategies from hotter climates, such as keeping windows and blinds closed during peak heat hours, installing external shutters, and increasing vegetation to provide shade and absorb heat. The Mayor's upcoming London Plan must focus on enhancing resilience to heat and climate change, ensuring that new and existing buildings are better suited for high temperatures, and preventing developments that exacerbate the urban heat island effect. Failure to act could lead to increased loss of life and livelihoods in the city.