Belgium Records First Tropical Day of 2026 at 30.4°C

Belgium officially recorded its first tropical day of 2026 on Tuesday, 26 May, as the mercury at the Royal Meteorological Institute (KMI) station in Ukkel reached 30.4°C. The milestone also shattered the previous daily record for 26 May, which had stood at 29.0°C since 1985, according to VRT NWS.

Temperatures across the country climbed as high as 31°C, with the KMI forecasting up to 32°C in the northeastern regions. Coastal areas remained cooler at approximately 25°C due to a persistent sea breeze.

A Record-Breaking Day

The day’s achievement followed a weekend of steadily rising temperatures. On Saturday, 23 May, the highest temperature of the weekend was recorded in Kleine Brogel at 30.9°C. Sunday saw Ukkel reach 28.7°C, and on Monday — Pinkster Monday — the capital’s measuring station equalled the 1953 daily record of 29.3°C.

“After equalling the daily record yesterday — 29.3 degrees Celsius from 1953 — we are also experiencing the warmest 26 May since the start of observations,” said VRT-weerman Bram Verbruggen, as reported by VRT NWS.

KMI-weerman David Dehenauw confirmed the milestone on social media: “In Ukkel, the 30-degree mark has just been reached. This makes the first tropical day of 2026 a fact,” HLN reported.

What Defines a Tropical Day?

In Belgium, a “tropical day” (tropische dag) is officially defined as a day when the maximum temperature at the KMI’s Ukkel station reaches or exceeds 30°C. This is distinct from a “summer day” (zomerse dag, ≥25°C) and a “heatwave” (hittegolf), which requires at least three tropical days within a five-day period where minimum temperatures also remain above certain thresholds.

Meteorologists confirmed that conditions for an official heatwave were not expected to be met. “For a heatwave you need to reach 30 degrees three times in a series of at least 25 degrees over five consecutive days. The baseline scenario is that we won’t get that,” Dehenauw explained to Redactie24.

European Heat Dome Context

The warm weather was driven by a blocking high-pressure system, colloquially termed a “heat dome” (hittekoepel), parked over parts of western Europe. While Belgium experienced notable warmth, more extreme conditions were recorded elsewhere on the continent.

The United Kingdom recorded its warmest May day on record, with temperatures reaching 33.5°C near London. France saw temperatures exceeding 35°C in the southwest, where two heat-related fatalities were reported — a 28-year-old woman in Lyon who died from heatstroke during a sporting event, and a 53-year-old man in Paris who suffered a fatal heart attack while running.

Dehenauw downplayed the term “heat dome” as nothing new in meteorological terms. “‘Heat dome’ is a term that has been used in the media in recent years for a blocking high-pressure area, as we have known it for years in meteorology. So in itself, that’s not so special,” he told Redactie24.

Public Health Precautions

The KMI issued a heat warning for Belgium, with the UV Index reaching a very high 7.3. Health authorities advised residents to stay hydrated, avoid midday sun, and use adequate sun protection. Coastal towns activated heat plans, with extra train services to the coast and monitoring of crowds.

What’s Next?

Temperatures are expected to remain warm but decline slightly from Wednesday, 27 May, with forecasts of 23-27°C and a possible isolated thunderstorm in the southeast. Thursday and Friday will see sunny conditions with highs between 23-29°C. The weekend of 30-31 May brings increased cloud cover and a chance of thunderstorms, with temperatures dropping to a more seasonal 23-27°C.

The first tropical day of 2026 arriving on 26 May is notably early compared to recent years — the first tropical day fell on 12 June in 2025, 26 June in 2024, and 9 June in 2023. While not unprecedented, the trend of progressively earlier tropical days has drawn attention from meteorologists and climate observers alike.