Amsterdam has an oceanic climate, strongly influenced by its proximity to the North Sea to the west, with prevailing westerly winds. Winters are mild. Amsterdam, as well as most of the North-Holland province, lies in USDA Hardiness zone 8b. Frosts mainly occur during spells of easterly or northeasterly winds from the inner European continent. Even then, because Amsterdam is surrounded on three sides by large bodies of water, as well as having a significant heat-island effect, nights rarely fall below −5 °C (23 °F), while it could easily be −12 °C (10 °F) in Hilversum, 25 kilometres southeast. Summers are moderately warm but rarely hot. The average daily high in August is 22.1 °C (71.8 °F), and30 °C (86 °F) or higher is only measured on average on 2.5 days, placing Amsterdam in AHS Heat Zone 2. The record extremes range from −24 °C (−11 °F) to 36.8 °C (98.2 °F). Days with measurable precipitation are common, on average 187 days per year. Amsterdam's average annual precipitation is 915 millimetres (36.0 in). A large part of this precipitation falls as light rain or brief showers. Cloudy and damp days are common during the cooler months of October through March
