Heat warning – Orange alert from Thursday 13 August 2026

Based on MeteoLux forecasts, an orange heat alert will be in force in the south of the country from Thursday 13 August 2026. The alert is currently expected to remain in force until and including Friday 14 August.

In order to assess the weather situation and its potential impact on the population, the Cell for the Assessment of Weather and Flood Risks (Cellule d'évaluation des risques intempéries et inondations, CERI) met on Wednesday morning.

A period of sustained heat

According to current forecasts, very hot conditions will gradually affect the entire country. High thermal stress is expected in the south of the country, with the highest temperatures forecast for Thursday (34–36°C) and Friday (35–37°C). Night-time temperatures will also remain relatively high (18–21°C), limiting overnight cooling.

In the north of the country, this level of thermal stress will only be reached locally.

The heat may cause fatigue and exhaustion, particularly in the event of prolonged exposure to the sun or physical activity.

An orange alert is issued when high thermal stress is expected for at least two consecutive days. The assessment is based in particular on a feels-like temperature indicator, which takes into account various weather parameters such as air temperature, humidity, wind and solar radiation.

The public authorities draw attention to the potential health effects of heat and call on the public to take appropriate measures to limit its impact.

Possible consequences

• Health risks, particularly for older people, young children, people with chronic illnesses or mental health conditions, people taking certain medications, and people who are isolated.
• Risk of dehydration and heatstroke, particularly following prolonged exposure to heat or intense physical activity.

Recommended behaviour

• Drink water regularly throughout the day (at least 1.5 litres of water per day).
• Avoid prolonged and direct exposure to the sun during the hottest hours (11am–9pm).
• Keep your home as cool as possible by closing shutters, curtains and windows during the day and ventilating at night.
• Opt for light meals with a high water content, particularly fruit and vegetables.
• Wear light, loose-fitting and light-coloured clothing and cover your head when going outside.
• Limit physical activity and avoid strenuous exercise during the hottest periods of the day.
• Stay in cool or air-conditioned places whenever possible.
• Look out for vulnerable or sensitive people in your surroundings and check on them regularly.

If you experience symptoms suggesting heatstroke — high body temperature, headache, nausea, confusion, drowsiness or loss of consciousness — seek medical attention promptly. In an emergency, call 112.

Increased vigilance regarding the risk of vegetation fires

The Corps grand-ducal d'incendie et de secours (CGDIS) draws attention to the increased risk of vegetation fires during periods of high temperatures and dry conditions. The public is urged to exercise particular caution during outdoor activities and to avoid any behaviour that could cause a fire.

Save water

The Administration de la gestion de l'eau (AGE) reminds the public that the national vigilance phase concerning drinking water supply has been in force since 10 July 2026.

High temperatures can lead to increased water consumption while water resources remain under pressure. Citizens, businesses and local authorities are therefore encouraged to continue their efforts to save water, in particular by limiting non-essential uses of drinking water and complying with any instructions issued by local authorities.

Further information

www.infocrise.lu; www.lu-alert.lu; www.meteolux.lu; www.santesecu.lu/canicule; www.waasser.lu

Participants in the CERI

Haut-Commissariat à la protection nationale (HCPN), MeteoLux, Direction de la santé, Corps grand-ducal d'incendie et de secours (CGDIS)

Released by the Cellule d'évaluation des risques intempéries et inondations (CERI)