Even in a high latitude small country by the sea heat related health problems may occur. In 2006 two people died in a major International Four-Day Walking Event (40,000 people walk 40km per day around the city of Nijmegen ) because of temperatures close to 35 degrees Celsius. The event was cancelled after the first day and 40000 people were asked to go home. This, as well as the general heat problems during 2003 and 2006, for mainly elderly people, triggered the Government to develop a Heat Plan: a set of actions to be taken in case of extreme heat conditions.

Part of the Heat Plan is a Heat and Health Warning System (HHWS). In 2007 the Netherlands Weather Service KNMI and the National Health Institute RIVM have started such an HHWS. KNMI is responsible for the meteorological part whereas RIVM will judge the health consequences, resulting in a joint warning. The early warning, in probabilistic form, is based on the ECMWF ensemble system and will be distributed to all the Health Stakeholders. The final warning, when the Heat Wave is imminent, will also be issued to the General Public. The target group consists of people over 65 year of age, and special attention is given to the urban area. The population of the Netherlands is 16.5 million living in an area of 150x300km , of which most people live in the big cities.

In this presentation we will discuss experiences so far, and the possible integration into a European system. We will also discuss some work on the quest for a proper definition of a heat wave, in collaboration with the Euroheat project.