The Netherlands has recorded its hottest summer since national measurements began in 1901, according to data from the Royal Netherlands Meteorological Institute, known as KNMI. The average temperature across June, July and August at the benchmark station in De Bilt reached 19.3 degrees Celsius, surpassing the previous record of 18.9 degrees set in 2018. KNMI data made the result certain before August ended.
The record followed repeated episodes of extreme heat across western and southern Europe. In June, KNMI issued the Netherlands' first code red warning for extreme heat as a prolonged hot spell disrupted roads and rail services, led schools and events to close, and increased pressure on emergency medical care. Further heatwaves and unusually dry conditions continued through the summer.
Warm nights were among the season's most exceptional features. KNMI climate specialist Peter Siegmund told NOS that the country logged its highest number of days above 35 degrees and a record number of tropical days. In Maastricht, temperatures did not fall below 22 degrees for three consecutive nights, a sequence never previously measured in the Netherlands, even for two nights.
KNMI's August observations also show how persistent the warmth has been. Through August 26, De Bilt had a monthly mean of 19.1 degrees, compared with the 1991-2020 normal of 17.8 degrees. The station had accumulated 228.3 hours of sunshine and only 38.3 millimetres of rain by that point, reinforcing the broader picture of a warm and dry summer.
Siegmund estimated that a summer with this average temperature now has a recurrence interval of about five years in the current climate, and said that interval is likely to shorten as warming continues. Under KNMI's high-emissions scenario, a summer like 2026 could represent average conditions around 2050. He stressed that future temperatures still depend strongly on greenhouse-gas emissions.
KNMI scenarios indicate that the difference between low and high emissions pathways could amount to about one degree by 2050 and four degrees by 2100. Forecasters cannot yet determine whether the hot, dry summer will produce an extreme autumn, but the Netherlands has an exceptionally warm nearby sea, which can supply energy and moisture for heavy rainfall. Final seasonal figures will follow after August closes.
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