Over the past 50 years, the weather in the Netherlands has changed. Particularly, the sunnier springs with drier air have increased the risk of wildfires. This is evident from a preliminary study by the KNMI on the historical risk of wildfires in the Netherlands.

Dry Spring 2025 

The wildfires of the past weeks attracted a lot of attention. For example, the fire on the Eder Heide on April 3 and the one in the Drunense Duinen on April 12. After an exceptionally wet period that began in July 2023 and lasted for a year and a half, a very dry period began in March of this year. March 2025 was even the driest March since the start of official KNMI measurements in De Bilt, and also the sunniest March since 1965. Humidity was low, and evaporation was 50 percent higher than the long-term average. The wind often came from the east, bringing dry continental air. These are conditions under which the Netherlands becomes susceptible to wildfires. The wildfire on the Eder Heide was also well monitored with the new Meteosat Third Generation weather satellite and the KNMI cloud meters (ceilometers), as the video below shows. 

Wildfires in the Netherlands 

Wildfires are - contrary to popular belief - not a phenomenon limited to countries around the Mediterranean, California, Canada, Siberia, or Australia. Wildfires also occur in the Netherlands. They are, however, much smaller in scale than the devastating wildfires in the aforementioned areas. Late spring and early summer are the months when wildfires occur relatively often in the Netherlands. During this time, vegetation is often still dry because sap flows have not yet started. Weather conditions such as little precipitation, low humidity and sufficient sun and wind play a key role in wildfire danger.

Wildfires and Climate Change in the Netherlands 

An interesting question is whether the changing climate in recent years has increased the risk of wildfires emerging. It has certainly become drier and sunnier. The increased dryness in the interior can certainly be attributed in part to the warming climate. What the role of increased solar radiation, fewer aerosols, changes in soil moisture and vegetation, and changes in weather patterns is, remains unclear. For emergency services, it is particularly important to know how much the chances of fires have changed, what the causes are, and when the risk is highest. A few years ago we already noted that the number of fire-sensitive days - days with relative humidity below 50 percent - has increased since 1950.

To investigate this in more detail, new data techniques and data on reported wildfires (since 2017) have been used to analyze predictability. The reported wildfires have been linked to weather data, and relationships have been derived between wildfires and that weather data. These relationships have then been applied to historical weather data since 1960: “back to the future”. Note that these are preliminary research results. Relative humidity and wind appear to be the main predictors of (the risk of) wildfires. 

Image 1 shows how the chances vary from year to year, relative to the average of the period. Since 2018, there have been many years with above-average chances of wildfires, up to twice as high. And 2025 is not included in that. If we break it down by month - Image 2 - we see that it is mainly specific months in which the chance of wildfires is high. Not surprisingly, the weather in the Netherlands is very changeable and extreme drought - periods with little to no precipitation - usually lasts no longer than a few weeks. Well-known recent dry months stand out: the heatwave of July 2018, the dry and sunny April of both 2019 and 2020, the sunny March in 2022, and the dry, warm, and sunny June in 2023. The chances of wildfires were also above average for the dry March of 2025. At the same time, the chances of wildfires in 2024 were low. That began after the sunny June 2023 and did not stop until the end of February 2025. During that period, it was also extremely wet in the Netherlands.