A yellow weather alert, originally issued for Thursday 9 July from 12pm until midnight Saturday, has now been extended until midnight on Tuesday, nationwide.
The previous alert applied only to southern Luxembourg, but Monday and Tuesday's temperatures are expected to affect the entire country.
Forecasters warn that moderate thermal stress is expected during this period, with fatigue and heat exhaustion possible for people spending prolonged periods outdoors or undertaking strenuous physical activity.
While the conditions are typical for the region at this time of year, they may become locally hazardous. Residents and visitors are advised to take sensible precautions, including staying hydrated, avoiding excessive exertion during the warmest part of the day where possible, and checking on vulnerable people.
Authorities also recommend keeping up to date with the latest forecasts and weather warnings, particularly for those planning outdoor work, sporting activities or other weather-sensitive events.
