Rare second heatwave recorded at official weather station in the Netherlands

A heatwave has now been officially declared at De Bilt, where the temperature reached 25.2 degrees Celsius at around 10:40 a.m. In recent days, the main weather station had already recorded summer days with highs of at least 25 degrees Celsius, and on three of those days it was even tropically warm, with a minimum of 30 degrees Celsius. This is the second heatwave of the year, something Weeronline calls “very unusual.”

Since weather measurements began in 1901, only the summers of 1941, 2006, 2018, and 2019 have had two official heatwaves. A heatwave requires a series of at least five summer days with temperatures of 25 degrees Celsius or higher, with at least three of those days reaching tropical temperatures of 30 degrees Celsius or higher.

This is the 32nd heatwave ever recorded at De Bilt, which is often considered the meteorological average for the country, as it is is the basis for official national records and is home to headquarters of the national meteorological institute of the Netherlands, the KNMI.

There is also a heatwave at the regional level, which is more common. Last year was the first time in years without a single regional heatwave in the Netherlands. By contrast, there were three regional heatwaves in 2023.

The current official heatwave is expected to end on Saturday, with temperatures at De Bilt forecast to stay below 22 degrees Celsius.

The longest heatwave at De Bilt lasted 18 days, from July 29 to August 15, 1975. The highest number of regional heatwaves in a single year occurred in Maastricht in 1947, with five. The last of these remains the latest heatwave on record in the Netherlands, from September 11 to September 17.