National Heatwave Plan to reduce heat-health risks in the Netherlands

The Dutch National Heatwave Plan was drafted after a severe heatwave in 2006 and published in 2007; the first national alert was issued in 2010. By mid-2025, it had been activated 18 times nationally.

In 2024–2025, the Dutch National Institute for Public Health and the Environment (RIVM) has conducted its first comprehensive process and outcome evaluation of the plan. The evaluation consists of four sub-studies: an epidemiological analysis of heat-related mortality; a study on the public’s understanding of the Heatwave Plan’s messaging; a scenario exercise assessing preparedness for extreme heat events; and a behavioural study (forthcoming) investigating how target groups perceive and respond to heat warnings.

The Trigger logic and operational chain

The Dutch plan links real-time weather surveillance to a tiered public-health response:

• The plan is triggered when the Royal Netherlands Meteorological Institute (KNMI) forecasts a spell of hot weather of +/- four consecutive days ≥ 27 °C. Not only daytime temperature plays a role in activation; night time temperature and humidity are also taken into account.
• When these conditions are met, the official activation is communicated via a national heat alert email issued by the Dutch National Institute for Public Health and the Environment (RIVM) in consultation with KNMI, followed  by a decentralized cascading of further notifications to (home- )care providers, municipalities and organisations like the Dutch Red Cross.
• Recipients use this information at their own discretion to take action (e.g., increase check-ins on frail or elderly people, adjusting work schedules, issuing hydration and cooling advice etc.) and inform their stakeholders.
• Public communication is supported through joint messaging from RIVM and KNMI, often amplified by media coverage.
• Daily situation updates are circulated through the pre-agreed channels until temperatures drop below the trigger threshold and the alert phase is terminated.
• The target group for the heatwave plan constitute those people (both professionals and informal caregivers) taking care or looking after vulnerable individuals (e.g. the elderly, people with chronic illnesses, very young children, overweight people or pregnant women).

The Epidemiological analysis (published)

To assess whether the National Heatwave Plan had an impact on the relationship between heat and mortality in the Netherlands, the research team compared the ten-year period before (2000–2009), and after (2010–2019) the first activation of the plan using daily national data. Using statistical models that account for long-term trends, seasonal patterns and lag effects, the researchers assessed how the risk of heat-related deaths changed over time. Analyses were stratified by age group, sex, neighbourhood socioeconomic status (SES), and degree of urbanisation. Based on these models, the heat-attributable mortality risk was calculated. These risks represent the additional mortality risk at a given temperature compared with the minimum mortality temperature (the temperature at which the lowest mortality risk is observed).

High level results

• Overall, the heat–mortality risk curve shifted downwards after 2010.
• Excess risk at high temperatures dropped, and heat-attributable deaths fell from ~7,000 (2000–2009) to ~4,300 (2010–2019) despite population growth.
• Biggest relative declines: ≥75+ age groups, women (previously higher risk), and low-SES neighbourhoods (risk now similar across SES strata).

Attribution nuances

The evaluation suggests that mortality risks on hot days substantially decreased since the first activation of the heatwave plan. However, the decline cannot be solely ascribed to the National Heatwave Plan. Earlier heatwaves (2003, 2006) have led to increased public awareness and broader adaptation measures (e.g., increased use of air-conditioning, behavioural changes, and improvements in health care), which might also played a role. While it is difficult to isolate the exact impact of the Heatwave Plan, the available evidence supports its high relevance and usefulness.

Scenario Exercise on Extreme Heat Events (published)

The frequency and intensity of extreme heat events in the Netherlands is expected to rise due to climate change. Despite having a National Heatwave Plan, extreme heat in July 2019 (reaching 40°C+ for the first time in the country) still resulted in the single highest summer daily mortality, underscoring remaining vulnerability at temperature extremes. To assess the Netherlands’ level of preparedness for extreme heat, the RIVM developed an extreme heat or “code red” scenario. This fictional yet realistic scenario describes a situation of extreme heat with multiple impacts occurring almost simultaneously. The RIVM presented the scenario in a workshop with various heat experts and stakeholders at national, regional, and local levels to explore whether the Netherlands is adequately prepared for such a "code red" heat scenario.

High level insights

• No criteria for code red: The Royal Meteorological Institute (KNMI) uses a color-coded warning system for extreme weather, with red ("code red") indicating potentially disruptive societal impacts. However, there is no specific meteorological criteria for issuing a code red in the case of heat.
• No shared objective: Extreme heat has a unique profile- it may last for a long time, affecting larger geographies, yet people tend to underestimate the risk of heat -still considering it “pleasant weather”.  Heat can trigger cascading effects across sectors, ranging from increased hospital admissions, transport disruptions, to agricultural challenges. It is difficult to define a single national objective for extreme heat preparedness given its wide-ranging impact. However, without clear objectives, prioritizing actions or investments remain difficult.
• Limitations of Standard Crisis Response: Measures like staying indoors (effective for storms) may be unsafe during heatwaves. Existing plans, including the National Heatwave Plan, do not specify actions for code red scenarios. The workshop also revealed unclear role divisions between national and regional authorities.

The Evaluation of Heatwave Plan Messaging (published)

The RIVM examined how the communication sent post-activation is being received and understood by Dutch people, and whether it prompts them to take protective actions. In addition, an alternative infographic featuring the core message ‘Look after each other’ was developed and tested. The RIVM conducted a survey at the beginning and end of summer 2024 with a representative sample of the Dutch population.

Key insights

• Awareness is high: most people understand the health risks of heat, especially for vulnerable groups.
• Behavioural intent is promising: about half of those surveyed said the core slogan “Look after each other when it is hot” encourages them to check on vulnerable people once the plan is activated.
• The message resonates: the alternative infographic (“Look after each other when it’s hot”) broadened engagement beyond individuals who that already provide care.