More and more days of exceptionally hard rainfall measured in the Netherlands this year

It is increasingly raining exceptionally hard in the Netherlands. There were eight days up to July this year with at least 50 millimeters of rain locally. That is twice as many days as usual, according to research from ANP based on numbers provided by the weather institute KNMI.

If a day has 50 millimeters of rain, which is measured locally at one of the weather stations, then meteorologists consider it a day with heavy rainfall. This has happened more often in the last few years.

In the 1970s, '80s, and '90s, there was an average of three days of heavy rainfall per year. This is currently almost six. A new world record was set in 2021 with 13 days of extreme rainfall.

May had the most days with large showers thus far this year. The day with the most rainfall was on May 22. Eight rain measuring stations saw 66 millimeters of rain. Usually, there are around 55 millimeters for the whole month of May.

"The Netherlands has gotten warmer in the last decades. Warmer air can contain more moisture. This leads to more rain now falling from a shower than before," explains climate expert Peter Siegmund of the KNMI. "According to research by the KNMI, the number of heavy showers will increase further in the future."

Nine of the 12 provinces had a lot of rain in at least one place in 24 hours. In Noord-Holland, Groningen, and North Brabant, exceptionally high amounts of rain were measured in seven and six different locations, respectively.

The provinces of Utrecht, Flevoland, and Friesland have not seen a day with heavy rainfall. Yet it is still possible that there have been downpours in these provinces, said Siegmund. "The KNMI measures the downpour at over 300 locations spread out over the whole country, but downpours can sometimes be so local that the network does not always see them."

ANP analyses the historical data of over 240 KNMI downpour measuring stations for this research to see how many days with heavy precipitation there were yearly. They looked at the first seven months of the year between 1951 and 2024 for this.