Public warning sirens
The Netherlands has a public warning system. All over the Netherlands, the public warning sirens are tested at noon (12:00 p.m.) on the first Monday of every month. The siren sounds for 1 minute and 26 seconds without interruption. This is a test signal so there is nothing to worry about. The sirens are never tested on public holidays or Remembrance Day, even if they fall on the first Monday of the month.
In an emergency, the siren will sound repeatedly!
If the siren sounds repeatedly or if it sounds at any other time, it means that there is an emergency of some kind. You may also hear a warning over the public address system or from a loudspeaker van. Go indoors immediately. Close all doors and windows and turn on the radio or TV and find the emergency station. Follow the instructions and advice of the public authorities.
For more details, see government.nl
NL-Alert
NL-Alert is a government service for emergency situations. It sends a warning if there is a disaster situation in your vicinity, such as a major fire or heavy weather, and tells you what to do. NL-Alert SMS messages can be sent to your mobile phone, and you can also see them on a growing number of digital advertising displays and digital signs at train, bus, tram, and metro stops.
When receiving an NL-Alert, your mobile will emit a penetrating alarm sound. The text message will state what is going on and what you should do. NL-Alert is based on cell broadcast technology, which can operate even if the network is overloaded. NL-Alert is free and anonymous. Your name and telephone number are not required and thus remain unknown.
If you receive or see an NL-Alert, follow the advice in the message. Inform people in your direct vicinity if they have not yet seen the alert.
National NL-Alert sends test messages in July and December each year.
For more information, see nl-alert.nl
AMBER alert and Missing Child (Vermist Kind) Alert
If a child is missing, the police may issue a Vermist Kind Alert (Missing Child Alert) if there is concern for the well-being of the child or an AMBER Alert if their life is believed to be in danger.
If one of these alerts is issued, the police are appealing to everyone to look out for the child.
Outdoor swimming areas
Zwemwater.nl is a joint website of the Ministry of Infrastructure and Water Management, the provinces, and the water boards. During the swimming season, from 1 May to 1 October, the water quality of official outdoor swimming areas is regularly measured and assessed for hygiene and safety. The website has a map showing all the official outdoor swimming areas in the Netherlands along with details of the water quality and safety. This website is in Dutch but has icons to illustrate water quality.
Weather
The Royal Netherlands Meteorological Institute (Koninklijk Nederlands Meteorologisch Instituut - KNMI) is the national research and information center for meteorology, climate and seismology. The KNMI provides advice and warnings about the weather, climate and seismology.
The KNMI has a weather alert system for weather situations that pose a risk, such as heavy winds, mist or ice. They use the standard international warning color code system and issue warnings per province.
Code green (groen) - Code yellow (geel) - Code orange (oranje) - Code red (rood)
You can see whether there are any weather alerts on the KNMI website and/or you can download the KNMI app to your phone.
There are also various weather apps you can download to see weather forecasts, such as Buienradar or Buienalarm, which show the forecasted timing of rain or snow showers.