Environment & Urbanization

World leading environmental and urban studies journal

Heatwave Guide for Cities

R Singh, J Arrighi, E Jjemba, K Strachan, M Spires, A Kadihasanoglu

Red Cross Red Crescent Climate Centre



This introductory guide, intended for city authorities, is practical and accessible. It’s full of policy recommendations, next steps, suggestions for further reading, short case studies, and simple graphics. Given its global scope and general recommendations, it would be useful for providing background or initiating discussions, rather than conducting detailed planning.

The report makes it clear why planning for heatwaves is urgent. It’s an often-underestimated risk, especially in countries that are accustomed to hot weather. This complacency is dangerous in light of the pace of climate change: “Climate projections indicate that if greenhouse gas emissions continue on their current pathway, by the year 2100 three out of four people on Earth could be subject to at least 20 days per year of potentially deadly heat and humidity levels” (page 20). And an “optimism bias” means that even vulnerable groups undervalue the risk they face. For instance, 72–94-year-olds with heat-sensitive medical conditions in Norwich, UK believe that others, not themselves, are especially at risk – partly because of overly general warnings. One way to take advantage of this optimism bias is to emphasize specific “adaptive efficacy” in suggesting individual behaviours. For example, telling people about the dangers of outdoor exercise in the afternoon is less effective than telling them about the benefits of avoiding exercise between 13.00 and 16.00 (page 55).

While rising heat is a problem the world over, extreme heat and heatwaves have to be defined locally. The report contrasts the examples of London, where heat-related deaths increase at 25°C, and the Indian plains, where the same threshold is reached at 40°C (page 12). The report also compares direct impacts of heatwaves, including dehydration and road melting, to indirect impacts, including surges in electricity demand and emergency room admissions. Together, these direct and indirect effects can lead not only to high death rates, but also to high costs; one estimate is that the 2013 heatwave in Nanjing, China, which lasted two weeks, cost yuan 27 billion (US$ 4 billion) in lost productivity. Of course, the financial losses hit certain groups the hardest, such as those on low incomes, ethnic minorities, and older people (page 15).

As for health impacts, deaths during a heat wave can extend into the tens of thousands. Most heat-related illnesses have to do with pre-existing respiratory and cardiac conditions. City dwellers face particular vulnerabilities due to the urban heat island effect and the complicating factor of air pollution. For instance, just opening windows may be unhealthy if air pollution is rampant (page 16).

Usefully, the guide provides a raft of good practices and success stories to learn from. It’s clearly important to engage intra-city collaboration across departments, particularly planning, health, social services and emergency management services (page 14). (The recommendation to call on meteorology offices will be of limited use in countries without these institutions.) Across sectors, anticipatory funding needs to be included in city budgets and plans.

The nonprofit and private sectors should be engaged as well. For instance, companies could offer their air-conditioned buildings for private use, utilities should keep energy flowing to heat-affected households even in cases of non-payment, and employers should provide water points and extra breaks to employees during high heat.

It’s also important to pay attention to differential impacts. For instance, informal settlements are often unconnected to municipal water systems, increasing the risk of dehydration. Homes in precarious settlements, such as those with tin roofs, may not insulate residents well from heat. Low-income urban residents frequently work in physically demanding jobs with high sun exposure and with little access to healthcare. And a lack of cultural awareness could mean that certain populations are left out. For example, in the Kosad Awas settlement of Surat, India, women prefer to stay at home and are afraid to keep their windows open; and most residents work on short-term contracts that require them to keep working during peak heat periods (page 37).

The good news identified by the report is that warning systems can be improved for many people, the majority of the world lives in a place where extreme heat is at least somewhat predictable (page 40), and cities are well-positioned to address the interlinked factors in heat vulnerability. Some cities have adopted beneficial practices. In Philadelphia, USA, preventive actions in the mid-‘90s saved an average of two lives each day during a heatwave. They were also very cost-effective (amounting to less than $10,000 a day) as most of the activities could be folded into city employees’ work or undertaken by volunteers. And in Ahmedabad, India, heat warnings are posted on the sides of rickshaws, while one hospital relocated the maternity ward from the fourth floor to the cooler ground floor following a heatwave. (Infants and pregnant and lactating women are especially vulnerable to heat.)

As the introductory message states (page 3), expressing the scale of the problem itself and of the tools to address it:

“Cities are on the front lines of this public health emergency and are thus crucial in leading the fight to prevent unnecessary deaths from heat.”


Available from:



Further reading:

Climate and Development Knowledge Network (2014), Addressing Heat-Related Health Risks in Urban India: Ahmedabad’s Heat Action Plan, available at http://bit.ly/cdknheat.

Mabon, Leslie and Wan-yu Shih (2018), “Mapping the socio-political landscape of heat mitigation through urban greenspaces: the case of Taipei Metropolis”, Environment and Urbanization, available at https://journals.sagepub.com/doi/full/10.1177/0956247818767318.

Miner, Mark J, Robert A Taylor, Cassandra Jones and Patrick E Phelan (2016), “Efficiency, economics, and the urban heat island”, Environment and Urbanization Vol 29, No 1, pages 183–194, available at https://journals.sagepub.com/doi/full/10.1177/0956247816655676.


Book note prepared by Christine Ro

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