Heatwaves are deadly disasters that are increasingly common and can seriously affect human health and well-being. When a heatwave strikes, the most vulnerable are the most impacted. In the past decade severe heatwaves have been responsible for numerous fatalities, including over 1,500 deaths in India in 2015. These are likely underestimates because there is no systematic way to count deaths from heatwaves.

Their impacts are on the rise globally due to climate change. Every year, heatwaves claim the lives of infants, the elderly, and people with chronic health conditions. What is unacceptable about this silent emergency is that simple, low-cost actions – ordinary citizens checking on vulnerable neighbours, for example – can save lives during episodes of extreme heat. Urgent, timely action at scale during a heatwave can drastically reduce deaths due to extreme heat.

As many as 5 billion people live in areas of the world where heatwaves can be forecast before they happen, which means we have time to take early action to save lives. People living in urban areas are amongst the hardest hit when a heatwave occurs because these areas are hotter than the surrounding countryside.

Over half the world now lives in urban areas and this is projected to increase to two-thirds by 2050. It is therefore increasingly important to be aware of the dangers that heatwaves can pose, to understand the vulnerability of specific groups, and to take practical action to save human lives.

This guide by Red Cross Red Crescent (RCRC) branches is based on the comprehensive Heatwave Guide for Cities but it is tailored towards practical actions that can be led by the RCRC branches. It can be used on its own or alongside the Heatwave Guide for Cities, which helps city staff to understand heat risks, develop an early-warning system and adapt urban-planning practices.

This guide is intended to help staff and volunteers in RCRC branches understand the heat risks they face, work with partners to prepare for heat action, and integrate simple, low-cost, lifesaving actions into routine branch activities. This would help in preparing for, and responding to, heatwaves in towns and cities.

While heatwaves can affect both rural and urban areas, this guide is tailored towards actions in urban areas. Temperatures in towns and cities tend to be hotter than the surrounding rural areas due to the many surfaces – such as densely packed buildings, roads and pavements – that absorb heat and release it slowly. This effect makes towns and cities hotter for longer. A branch located in a rural area may choose to modify some of the actions to be better suited for this area.

The guide is structured to be easy to navigate – following a simple roadmap. The main sections are Understanding Heatwaves that provides basic information on heatwaves, high-risk locations and vulnerable groups; Preparing for a Heatwave focused on partnerships with city stakeholders; During the heatwave which outlines actions to help reduce the risk of heat impacts among various vulnerable groups; and Taking Stock and Lessons Learnt that provides guidance on conducting an after-action review as well as integrating learning into Preparing for the Next Heatwave that is the final section of this guide.

In each section there are activity sheets, action cards and case studies that can support you in your own planning process. These different resources are indicated by these symbols.

The first section on ‘Understanding heatwaves’ deals with what is a heatwave, who is vulnerable to extreme heat, where is it the hottest, and how to monitor extreme heat. The definition of heatwave is discussed here. A heatwave is an often-deadly disaster which results from unusually high temperatures, or high temperatures in combination with high humidity, which can be dangerous to health. Heatwaves typically have a noticeable start and end, last for a period of days and have an impact on human activities and health.

There is no single, universal definition for a heatwave because different temperatures often have varying impacts in different parts of the world. In the plains of India, the temperature must be higher than 40°C to qualify as a heatwave. High temperatures at night can be an important factor in determining a heatwave because it is harder for the human body to recover from high daytime temperatures without cool nights.

High humidity also makes it harder for sweat to evaporate off of the skin, one of the main mechanisms for the human body to cool off. Thus, temperature and humidity are both important when considering heat risk.

As per the guide, certain groups of people are typically at a higher risk, including older adults, very young children, pregnant and lactating women, people with pre-existing medical conditions, lower income populations, people working outside or cooking indoors in densely built areas such as informal settlements and shared occupancies, and people who are homeless. People in these groups may be more exposed to the heat and/or their bodies may have a harder time regulating the heat.

The built environment in a city – the concrete, asphalt and steel – can absorb heat and radiate it out, making temperatures in the city hotter than the surrounding rural areas. This is called the urban heat island effect. In some cities, there can also be parts of the city that are hotter than other areas. People living in these areas are more exposed to extreme heat, and may be at a higher risk of heat-related illness.

When working with local government to plan interventions, it is important to consider how temperatures can vary within the city, where temperatures are higher, and where more vulnerable people are located. These considerations help to target interventions. As a general approximation, areas with more green spaces tend to be cooler. Partnering with a local university can be a helpful way to identify specific information regarding your city.

The guide provides a detailed account of how to prepare for the next heatwave. Immediately after a heatwave is also a good time to build momentum for the next heatwave campaign by working closely with strategic partners – such as local government, universities, businesses, civil society, faith-based organizations and others – to update coordination plans for the next heatwave campaign, while capturing lessons from the most recent heatwave action.

This is also a good moment to focus strategically on fundraising for your next (improved) heatwave campaign, so that you can be ready to take effective action as soon as a heatwave is announced. It is equally important to incorporate heatwaves into the disaster preparedness and response plans of the National Societies and branches. In addition, branches can adjust existing tools such as Vulnerability and Capacity Assessments to add heatwaves.

In addition to planning for the next campaign, Red Cross branches should work with city officials to ensure that longer term urban planning measures reduce the intensity of future heat extremes as well as the impacts of heatwaves. Branch staff can play an important role in encouraging community advocates and liaising with local government authorities to adopt smart urban planning measures to reduce the overall temperature of the city.

Priority measures include protecting and increasing green spaces around the city, increasing access to public water points, retrofitting buildings with reflective roofs and passive cooling strategies as well as working with health systems to be prepared for future demands. These recommendations are detailed in the Heatwave Guide for Cities. It is a useful starting point to share this resource with local government counterparts in discussing longer term strategies to reduce heatwave risks.

The guide can be accessed here