Belgium Misses a Second Official Heatwave as Ukkel Peaks at 29.1 Degrees
The temperature at the KMI reference station in Ukkel peaked at 29.1°C on Wednesday 16 July 2026, falling 0.9 degrees short of the 30-degree threshold needed to declare a second official heatwave of the summer, Belgian media reported citing KMI measurements.
In 30 seconds
- Ukkel's temperature peaked at 29.1°C on Wednesday 16 July 2026, per KMI measurements cited by De Standaard, Het Nieuwsblad and De Morgen.
- The 30°C threshold required to sustain an official heatwave declaration was missed by 0.9 degrees.
- A Belgian heatwave requires at least five consecutive days of 25°C+ at Ukkel, including at least three days of 30°C+.
- Belgium recorded its first official heatwave of the season earlier in summer 2026, per De Standaard's framing of this episode as a missed second heatwave.
Ukkel (Uccle in French) is a Brussels municipality that hosts the headquarters and reference weather station of the KMI/IRM, Belgium's Royal Meteorological Institute. Its measurements serve as the country's official climate benchmark: national records, seasonal statistics and heatwave declarations are all based on readings taken there. Under the KMI definition, a Belgian heatwave requires at least five consecutive days of 25°C or more at Ukkel, including at least three days of 30°C or more. On 16 July 2026 the station peaked at 29.1°C, so the second heatwave of the summer was not declared, according to De Standaard, Het Nieuwsblad and De Morgen, all citing KMI data.
Background
Belgium has used Ukkel as its reference station for more than a century, allowing consistent comparison of warm episodes such as the benchmark summers of 1976, 2003 and the record-breaking heat of recent years, when Ukkel first passed 40°C in July 2019. KMI climate reporting documents a clear trend toward more frequent and more intense warm spells at the station over recent decades, which is why near-misses of the heatwave threshold now draw close public attention.
What to do
Heat advice applies regardless of the official label: hydrate, check on vulnerable neighbours and relatives, and follow guidance issued under Belgium's heat and ozone plans, which are activated by forecast conditions rather than the heatwave designation.
Impact
Regional — The measurement itself is taken in Brussels, but its significance is national: Flanders, Wallonia and the capital all read their summers through the Ukkel station. Local temperatures elsewhere in the country may have exceeded 29.1°C, but only the reference station counts for the official record.
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This story was assembled from verified evidence, with its sources and reasoning recorded as it was written.