Netherlands records first official summer day of 2026 as temperatures rise toward 30°C
The Netherlands recorded its first official summer day of 2026 on Friday, May 22, when temperatures in De Bilt reached 25.0 degrees. Warm, sunny conditions are expected to continue into the coming days, with forecasters predicting a hot and mostly dry run-up to the Pentecost holiday period. According to WeerOnline, inland temperatures are expected to reach 26–29 degrees, with local peaks up to 30 degrees in the south.
The first official summer day of 2026, registered at 3:40 p.m. in De Bilt, arrived slightly later than the average of around May 15.
Warm conditions were widespread across the country. Eindhoven recorded 27.2 degrees, the day's highest temperature. Earlier in May, summer-level warmth had already been measured at several locations, including 25.6 degrees in Gilze-Rijen, 25.3 degrees in Woensdrecht, 25.2 degrees in Hoek van Holland, and 25.1 degrees in Ell (Limburg) on May 1. De Bilt reached 23.6 degrees on that same day.
Forecasts indicate that warm, sunny weather will continue in the days ahead. On Saturday, inland temperatures are expected to reach 26 to 29 degrees, with local peaks up to 30 degrees in the south. Coastal areas will be cooler at 20 to 23 degrees due to sea breezes, while the Wadden Islands will see temperatures between 18 and 22 degrees.
Lifeguard services warn that warm air temperatures do not mean the water is warm, and swimmers remain at risk of hypothermia. Authorities also expect heavy traffic toward coastal areas.
On Sunday, during the Pentecost holiday period, conditions remain sunny and warm across much of the country. Inland temperatures are expected to range from 22 to 28 degrees, with the highest values in the south.
Northern coastal areas and the Wadden Islands are to stay cooler at around 19 to 21 degrees, with occasional light sea breezes again providing relief along parts of the western coast.
On Monday, which is also part of the Pentecost holiday period, sunny and dry conditions are to continue. Inland temperatures are expected to reach 25 to 28 degrees, while northern and coastal regions are to remain cooler at 18 to 20 degrees under the influence of northerly winds and the relatively cold North Sea.
Tuesday is forecast to bring another sunny and warm day, with highs of 25 to 30 degrees across central, eastern, and southern regions. Northern and western coastal areas will remain cooler at 22 to 25 degrees. The North Sea, at around 13 degrees, continues to suppress temperatures along the immediate coast.
After Tuesday, a brief cooldown is expected as cooler air moves in from the north to northeast. Wednesday brings temperatures of around 16 degrees in the north and 19–21 degrees elsewhere. Thursday becomes slightly milder, with temperatures ranging from 18 to 23 degrees. From Friday onward, temperatures are expected to rise again toward 20 to 25 degrees, with conditions remaining dry and sunny.
The first summer day coincides with the rollout of a new “heat intensity” index developed by the Royal Netherlands Meteorological Institute (KNMI). The system will be introduced in the KNMI app on June 2 and is designed to better reflect how heat is experienced by combining temperature, humidity, wind, and solar radiation into a single scale from 0 to 10.
The index is based on wet-bulb globe temperature and typically ranges from 3 to 6 in summer conditions. A maximum value of 10 has never been recorded in the northwestern Netherlands, and in De Bilt it has occurred only for about four hours across three days in 2005 and 2019.
TNO researcher Boris Kingma, who helped develop the index, said, “The same heat is a problem for one person and not for another.” The body regulates temperature by widening blood vessels, which increases strain on the heart as it circulates more blood. People with cardiovascular conditions or lower fitness levels may therefore struggle more in warm conditions, and physical activity can turn otherwise moderate heat into a health risk.
