June 2026 Was 3°C Warmer Than Normal in Belgium

June 2026 in Belgium was 3.1°C warmer than the historical average, according to data from the Royal Meteorological Institute (KMI) recorded at the Uccle weather station. The average temperature of 19.8°C makes it the second warmest June since records began in 1833, trailing only June 2023 (20.3°C), while June 2025 ranks third (19.3°C) — meaning the three hottest Junes in Belgian history have all occurred in the last four years, as VRT NWS reported.

A Month of Two Halves

The month presented two distinct faces. The first two weeks were relatively cool, but the second half from 16 to 30 June averaged 24.7°C — shattering the previous record of 22.2°C set in 2005. This temperature is more typical of Southern Europe than Belgium. The contrast was so stark that the intense 12-day heatwave from 17 to 28 June completely erased the cooler start from the monthly averages.

During the heatwave, Belgium recorded seven tropical days (maximum temperature exceeding 30°C). For context, the 1991-2020 average is only five tropical days in an entire year. The trend for tropical days has been rising sharply over recent decades, according to KMI data.

Record Warm Nights

Perhaps the most striking finding is that the average minimum temperature in June was 15.1°C — 3.1°C above normal and the highest June minimum temperature since records began in 1892. During the heatwave, one night saw the temperature in Uccle fail to drop below 24.1°C, an absolute record for a heatwave period. These exceptionally warm nights are particularly dangerous for public health, as they prevent the body from recovering from daytime heat exposure.

Hottest Day of 2026

On 26 June, Belgium recorded its hottest day of 2026 — 35.3°C in Uccle, breaking the previous record for that date (33.5°C set in 1976). This was the third consecutive day a 50-year-old daily record was broken, as The Brussels Times reported. KMI meteorologist David Dehenauw confirmed the reading, posting on X that “33.7 degrees in Uccle. Daily record from 1976 broken (33.5).”

Wet as Well as Warm

June was also notably wet, with 114 litres of rainfall per square metre in Uccle against a normal of approximately 70 L/m². The rainfall was driven by severe thunderstorms — on 27 June alone, 36 L/m² fell in a single event. “The wettest region lies on the Brussels-Antwerp-Noorderkempen axis, and further the area around Waregem, Kortrijk and Ypres,” Dehenauw told VRT NWS. “Between 140 and 180 percent of the normal value has fallen there.”

17th Consecutive Warm Month

June 2026 marks the 17th consecutive month where the average monthly temperature exceeded the normal value — a clear sign of persistent climate warming. The top three warmest Junes in Belgian history have all occurred since 2023, demonstrating an accelerating trend.

Long Heatwaves Now Five Times More Likely

A study published on 1 July by the Flemish Institute for Technological Research (VITO) found that the probability of a heatwave lasting at least 12 consecutive days has increased fivefold since the 1980s, as The Brussels Times reported. In the 1980s, the annual probability stood at around 3% (once every 30 years). Today, it has risen to approximately 14% (once every seven years). Since 1975, only seven heatwaves of at least 12 days have been recorded at Uccle.

“If we want to reduce the risks of increasingly frequent heatwaves, we need to act on two fronts,” said Hendrik Wouters of VITO. “We must further cut greenhouse gas emissions by continuing the transition to renewable energy, phasing out fossil fuels and making industry more sustainable. But we must also adapt to the warming that is already unavoidable.”

Future projections are stark: the most optimistic scenario foresees such heatwaves occurring once every four years after 2060, while the most pessimistic scenario points to heatwaves striking in two out of every three years.

European Context

The June heatwave was part of a continent-wide extreme weather event affecting at least 25 countries, with over 1,400 excess deaths reported across Europe, according to Wikipedia. A rapid attribution study by World Weather Attribution (WWA) found that the heatwave would have been “virtually impossible” 50 years ago without human-caused climate change, as RFI reported.

“The weather pattern itself is not particularly unusual, but the temperatures are — or at least they used to be, without human-induced climate change,” said Friederike Otto, professor of climate science at Imperial College London and co-founder of WWA. “Climate change is unequivocally to blame.”

Infrastructure Under Strain

The extreme heat exposed significant vulnerabilities in Belgium’s infrastructure. Electricity prices spiked to over €1/kWh at sunset on 24 June as air conditioning demand maxed out traditional power stations. Infrabel reduced high-speed train speeds from 300 km/h to 170 km/h between Brussels and Paris, adding 12 minutes to TGV journeys, as metal components expand in extreme heat. TEC suspended bus services during peak afternoon hours as much of its fleet lacks air conditioning. Tap water consumption peaked to its highest level in five years.

What’s Next

With the 17-month streak of above-normal temperatures showing no signs of breaking, and VITO’s projections pointing to increasingly frequent long heatwaves, the question facing Belgian policymakers is whether climate adaptation measures will keep pace with the accelerating warming trend. As Wouters put it: “The heatwave we have just experienced makes clear once again that climate adaptation is not a problem for the future, but a task for today.”