DEAR EDITOR,Worldwide, across the last five decades, the number of hot days, hot nights, and heat waves (hot weather which lasts for several days) has become more and more common.[1] In fact, considering the rate of climate change and environmental degradation on a global scale it has been anticipated that the scenario is going to worsen further with a substantial rise in the length, frequency, and intensity of heat waves.[1] Further, even though it is acknowledged that heat waves tend to affect cities more, the living standards and well-being of even rural people does take a massive toll.[12]Heat waves have resulted in a massive impact on the community, predominantly on the rising trends of mortality and morbidity.[34] In fact, in the months of May–June 2015 alone, more than 2500 and close to 1300 deaths have been reported in India and Karachi region of Pakistan.[56] Further, thousands of deaths and catastrophic consequences have even been attributed to heat waves across Europe and Russia in 2003 and 2010, respectively.[7] In addition, heat waves have shown detrimental effects on the infrastructure sector, clothes and food retailing, tourism, ecosystem, forest fires, and associated air pollution.[17]In response to the rising concerns associated with heat waves on the different dimensions of health and related sectors, the World Health Organization (WHO) and the World Meteorological Organization have jointly formulated guidelines pertaining to the Heat–Health Warning Systems (HHWS).[7] These guidelines possess global application and have been developed based on the recommendations of stakeholders from all concerned sectors (viz., climate, health, emergency-response agencies, policy makers, etc.).[7] This system can prove to be of extreme utility as heat waves lack the sudden violence of other disasters, but have become more frequent, and even result in serious consequences.[1] The HHWS can provide meteorological and/or climate-prediction-based information regarding the probability of forthcoming hot weather and thus can alert program managers and the general population to take timely actions to minimize the aftermaths of hot weather on health.[7] In fact, encouraging results have been reported among the nations which have successfully developed these early warning systems.[17]However, mere application of warning system will not deliver sustainable results unless it is adequately supported by earmarking a specific agency for carrying out meteorological activities with roles and responsibilities of other supportive agencies being clearly specified; effective inter-sectoral coordination with health sector taking a major lead in heat preventive efforts; linkages with existing voluntary organizations for outreach activities, especially for addressing the needs of vulnerable sections of society; involving members of community; encouraging widespread use of mass media, and communication technologies; strengthening of the existing infrastructure by ensuring proportionate funding and logistics support; establishing a comprehensive surveillance mechanism to monitor heat-related outcomes all across the nation; and advocating for development of climate-friendly urban cities.[12578]To conclude, on a global scale heat wave has been associated with significant negative impact on the health standards of people and different industries, and thus it is a sincere appeal by the WHO to nations to develop HHWS to reduce the after-effects of hot weather on health.