Climate

Amsterdam has a cool oceanic climate (Köppen climate classification Cfb), strongly influenced by its proximity to the North Sea to the west, with prevailing north-western winds and gales. Winter temperatures are mild, seldom below 0°C. Amsterdam, as well as most of North-Holland province, lies in USDA Hardiness zone 9, the northernmost such occurrence in continental Europe. Frosts mainly occur during spells of easterly or northeasterly winds from the inner European continent, from Scandinavia, Russia, or even Siberia. Even then, because Amsterdam is surrounded on three sides by large bodies of water, as well as enjoying a significant heat island effect, nights rarely fall below –5°C, while it could easily be –12°C in Hilversum, 25 kilometres southeast. Summers are moderately warm but rarely hot. The average daily high in August is 22°C, and 30°C or higher is only measured on average on 3 days, placing Amsterdam in AHS Heat zone 2. Days with measurable precipitation are common, on average 175 days per year. Nevertheless, Amsterdam’s average annual precipitation is less than 760 mm. Most of this precipitation is in the form of protracted drizzle or light rain, making cloudy and damp days common during the cooler months of October through March. Only the occasional European windstorm brings significant rain in a short period of time, requiring it to be pumped out to higher ground or to the seas around the city.