Deelen records first locally warm day of the year amid rising early heat trends
The Netherlands recorded its first locally warm day of the year on Saturday as temperatures in Deelen reached 20 degrees by 3 p.m. This marks the earliest occurrence of a warm day in the country, continuing a long-term trend of rising temperatures appearing earlier in the year.
To qualify as a warm day, temperatures must reach at least 20 degrees at one of the official weather stations in the country. The last warm day recorded in the Netherlands was on October 26, 2024, when temperatures in the central and southern regions exceeded 20 degrees.
Over the 1995-2024 climate period, the first warm day typically occurs on April 4. However, records show that warm days are arriving earlier in recent decades. In the 1991-2020 period, the average first warm day was April 6, while in 1981-2010, it was April 9. In the 1980s and 1990s, the first occurrence of 20 degrees or higher often did not happen until April 12.
Earlier on Saturday, a record-high temperature for this specific calendar date was also noted, further underlining the trend of rising temperatures.
In 2024, the first official warm day was recorded on April 6 in De Bilt, where the temperature reached 24.1 degrees, while a national high of 25.7 degrees was recorded elsewhere. This was also the first “summery” day of the year, meaning temperatures exceeded 25 degrees.
In contrast, 2023 saw a later arrival of warmth, with the first 20-degree day occurring on April 21. In 2022 and 2021, the first warm days were recorded on March 22 and March 29, respectively. One of the earliest warm days ever recorded was on February 27, 2019, when temperatures in Arcen reached 20.5 degrees, the highest winter temperature in Dutch history.
The earliest warm day on record in the Netherlands was on February 24, 1990, when temperatures in Oost-Maarland, Limburg, hit 20.4 degrees. Meanwhile, the latest arrival of a warm day occurred in 1941, when the first 20-degree reading was not recorded until May 18. In the northwestern coastal areas, warm temperatures have arrived even later in some years. In 1956, temperatures in that region did not reach 20 degrees until July 1.
On average, the southern and eastern Netherlands experience more than 100 warm days annually. Based on the 1995-2024 climate period, Eindhoven records an average of 111 warm days per year, Maastricht 104, Twente 101, and De Bilt 97. Northern cities see fewer warm days, with Eelde averaging 88, Leeuwarden 70, and Den Helder 60.
The summer of 2018 holds the record for the most warm days in a single year. That year, Gilze-Rijen recorded 147 warm days, while Arcen had 146. Several other locations, including Eindhoven, Maastricht, Twente, Hupsel, Ell, and Volkel, all recorded at least 140 warm days. De Bilt recorded 132 warm days in 2018, reflecting an exceptionally warm year.
