The Netherlands is set to experience a heatwave starting tomorrow, prompting the national heat plan activation by the RIVM. Temperatures are expected to reach 30-35 degrees Celsius across much of the country, with the southeast being the hottest. The RIVM advises vulnerable populations, particularly the elderly, to stay hydrated, keep homes cool, and limit outdoor activity during peak hours. While nights will remain warm, with temperatures not dropping below 23 degrees in cities, the heat will gradually subside starting Wednesday. Tuesday will feel humid despite slightly lower temperatures, with potential thunderstorms in the east. By the end of the week, temperatures will return to near the August average, with highs around 22 degrees Celsius and a generally dry forecast.