As Belgium is currently experiencing its seventh consecutive day of heatwave and temperatures are expected to stay up for a few more days, here are the answers to some frequently asked questions about Belgium's heatwaves past and present.
What is a heatwave exactly?
The Royal Meteorological Institute (RMI) speaks of a heatwave when the maximum temperatures in the Uccle measuring station reach at least 25 degrees for at least five days in a row. For at least three of those days, temperatures have to reach 30 degrees.
A heatwave continues until the day a maximum temperature of 25°C is no longer reached.
Is this Belgium's longest heatwave so far?
No, in fact, this is still quite short compared to Belgium's records. The top five of longest heatwaves in Belgium all lasted at least two weeks, according to weather reporter Frank Deboosere, who collected figures dating back to 1901.
This is the top five of the longest heatwaves in Belgium, according to the data.
19 days: 10 August to 28 August 1947
17 days: 22 June to 8 July 1976 and 5 August to 21 August 1997
16 days: 15 July to 30 July 2006
15 days: 20 July to 3 August 1911 and 13 July to 27 July 2018
14 days: 9 July to 22 July 1921 and 22 July to 4 August 1947
Is this heatwave breaking records in Belgium?
Yes. On Saturday 8 August, a temperature of 34.3 degrees was recorded in Uccle, which was later adjusted to 35.9 degrees, half a degree above the previous August record.
However, this was not Belgium's hottest day ever. The absolute heat record was reached on 25 July 2019, when a temperature of 39.7 degrees was reached.
The world heat record dates back to July 10, 1913, when a temperature of 56.7°C was recorded in Furnace Creek, Death Valley, United States.
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Which summer had the most heatwaves?
In 1947, four heatwaves were recorded, the first on starting in May, the last one in August.
7 days: 29 May to 4 June
6 days: 24 June to 29 June
14 days: 22 July to 4 August
19 days: 10 August to 28 August
In second place is last year, with three official heatwaves recorded in 2019. Third is the year before, with two heatwaves in 2018.
Do heatwaves happen every year?
No. Often, there are many consecutive "cool" summer years. The longest period without one in Belgium lasted 16 years, from 1959 to 1975.
From 1976 to 1990, there was no heatwave for a period of 14 years, and between 1911 and 1921, Belgium recorded no heatwaves for ten years.
Are heatwaves more frequent than they used to be?
Yes. Since 2015, Belgium records at least one heatwave every summer, and sometimes even two or three.
From 2011 to 2020, Belgium recorded ten heatwaves.
In the decade from 1941 to 1950, eight heatwaves were recorded, of which half took place in the summer of 1947.
Between 1990 and 2000, six heatwaves occurred.
Maïthé Chini
The Brussels Times
