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Belgian weather warnings: what the RMI colour codes mean

September 18, 2026
  • Yellow is presented in the reporting as a vigilance level for hazards including heat and drought.
  • The Royal Meteorological Institute provides Belgian weather forecasts, while Brussels drought vigilance involved the Regional Drought Cell.
  • A Belgian code-orange closure rule is not established by the reporting covered here.
  • Weather conditions can differ sharply between Belgian regions and can change during the day.
  • The colour must be read together with the hazard, location and timing.

What the colour codes mean

The reporting identifies yellow as a level of vigilance. On 31 July, 7sur7 said the yellow alert for high heat remained in force while temperatures were forecast to reach between 21°C and 29°C. The warning did not mean that every part of Belgium would experience identical conditions: showers were possible in the west and hills, alongside warmer weather elsewhere.

In Brussels, VRT NWS reported on 10 September that the yellow drought code remained active. It described this as a vigilance phase because conditions were still dry. The colour therefore appeared in connection with more than one hazard, including heat and drought. The reporting supplied here does not define the Belgian thresholds or operational meanings of orange and red.

Who issues warnings in Belgium

The Royal Meteorological Institute—called the RMI in English-language reporting and the IRM or KMI in the quoted French- and Dutch-language reports—provides Belgian weather forecasts and warnings. 7sur7 attributed the 31 July heat-warning update to the IRM, while VRT NWS attributed the 30 August forecast to the KMI.

The Brussels drought warning followed a different regional process. VRT NWS reported that the Regional Drought Cell decided to maintain the yellow drought code after a new assessment. This shows that weather forecasting and drought vigilance can involve separate official bodies and that a national weather forecast is not the only relevant warning source.

What a code orange actually closes

A Belgian closure linked specifically to a code orange is not established by the reporting covered here. The only orange alert mentioned was in France: HLN reported on 31 July that ten French departments received an orange warning for expected thunderstorms after weeks of heatwaves and wildfires.

That French example should not be treated as a Belgian closure rule. The Belgian examples describe yellow heat and drought vigilance, but do not attach a school, road, workplace, public-transport or other closure to those alerts. Decisions about closures therefore cannot be inferred from the colour alone.

Storms, heat and snow: how each is handled

The Belgian examples show that warnings are tied to specific hazards rather than to a single general condition. The 31 July yellow warning concerned high heat, while Brussels retained a yellow drought code in September because dry conditions continued. The two situations involved different risks and a different regional assessment.

Storm forecasts could also change during the day. VRT NWS reported on 30 August that clouds and sunny spells would be followed by showers moving in from the west, with locally possible thunderstorms in the evening. By contrast, the 18 September forecast cited by 7sur7 expected a dry afternoon nationwide after morning cloud, showers or drizzle in some areas. The supplied reporting contains no Belgian snow-warning example or snow-specific closure rule.

The coast, the Ardennes and why one forecast is not enough

Belgian forecasts can vary by location. On 18 September, 7sur7 reported a chance of a shower in the north, while the Ardennes and Belgian Lorraine were initially expected to be overcast with a risk of drizzle. The forecast then turned dry nationwide in the afternoon, with sunny spells between cloudy periods.

The hills also featured in the 31 July warning: 7sur7 said showers were possible in the west and the hills while heat kept the yellow alert in force. These examples show why a national headline forecast does not describe every local condition. For drought, Brussels had its own regional assessment and continued yellow vigilance on 10 September.

What to do when a warning is issued

The reporting supports checking the warning’s hazard, area and timing, rather than treating the colour as a complete description of conditions. A yellow heat alert can coexist with showers, and a forecast can shift from unsettled weather to a dry afternoon. Local differences were reported for the north, the west, the hills, the Ardennes and Belgian Lorraine.

For drought in Brussels, the relevant update came from the Regional Drought Cell, which maintained yellow vigilance after reviewing conditions. For ordinary weather, the RMI, IRM or KMI forecast is the key official reference identified in the reporting. The material covered here does not specify a general Belgian checklist or automatic closure procedure for orange or red warnings.

Common questions

What does a yellow weather warning mean in Belgium?

The reporting identifies yellow as a vigilance level, but its practical context depends on the hazard. On 31 July, a yellow alert remained in force for high heat while temperatures were forecast at 21°C to 29°C. In Brussels on 10 September, yellow referred to drought vigilance because conditions remained dry.

Who issues weather warnings in Belgium?

The Royal Meteorological Institute issues Belgian weather forecasts and warnings. It is referred to as the RMI in English, the IRM in the French-language report and the KMI in the Dutch-language report. Brussels drought vigilance was assessed by the Regional Drought Cell, which maintained the region’s yellow drought code.

Does a code orange automatically close schools or roads in Belgium?

No automatic Belgian closure rule is established in the reporting covered here. The only orange alert mentioned concerned ten French departments expecting thunderstorms. Belgian examples concerned yellow heat and drought warnings, without linking them to school, road, workplace or public-transport closures.

Can Belgium have different weather warnings in different regions?

Yes. Forecast conditions varied between areas in the examples. On 18 September, a shower was possible in the north, while the Ardennes and Belgian Lorraine faced morning cloud and drizzle risk before a dry afternoon nationwide. Brussels also retained its own yellow drought vigilance after a regional assessment.

What is the difference between a heat warning and a drought warning?

The examples concern different hazards. The 31 July yellow warning was linked to high heat, with temperatures forecast between 21°C and 29°C. Brussels’ yellow drought code remained active on 10 September because conditions were still dry. The drought decision came from the Regional Drought Cell.

What should I check during a Belgian weather warning?

Check the hazard, the affected area and the forecast timing. Belgian conditions can differ between the north, west, hills, Ardennes, Belgian Lorraine and Brussels. Forecasts can also change during the day: one update described evening thunderstorms, while another expected morning cloud or showers followed by a dry afternoon.

Compiled by the shortnews.be desk from our own reporting between 2026-07-30 and 2026-09-18, drawing on coverage by 7sur7, La Libre, HLN, VRT NWS. Last checked 18 September 2026.

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