Auckland experiences a unique climate that sits between oceanic and humid subtropical classifications, making it the warmest major city in New Zealand. Under the Köppen system, Auckland is classified as having an oceanic climate (Cfb), but the National Institute of Water and Atmospheric Research (NIWA) categorizes it as a humid subtropical climate with warm summers and mild winters. The city’s average high temperature peaks at 23.7°C (74.7°F) in February and dips to 14.7°C (58.5°F) in July. The highest temperature on record was 34.4°C (93.9°F) in February 2009, while the lowest, −3.9°C (25.0°F), was recorded during the winter.

Snowfall in Auckland is extremely rare, with the most significant event occurring on 27 July 1939, when Mount Eden saw up to 5 centimeters of snow. Minor snow flurries were also reported in 1930 and 2011, adding to the city's unique weather history. Frosts are infrequent and localized, with Henderson Riverpark averaging 27.4 frosty mornings per year compared to just 8.7 frosts annually at Auckland Airport.

Sea temperatures around Auckland vary between 21°C (70°F) in summer and 14°C (57°F) in winter, making the city's coastal areas a year-round attraction. Winds predominantly come from the southwest, and during the summer, a daily sea breeze adds a refreshing touch to the city’s mornings and afternoons. Fog is common, especially in the cooler months, with Whenuapai Airport experiencing an average of 44 fog days per year.

Auckland does face occasional air pollution, largely due to fine particle emissions and, at times, elevated carbon monoxide levels. Although maritime winds typically disperse pollutants, smog can sometimes appear, especially during calm winter days. This combination of subtropical warmth, coastal breezes, and occasional environmental challenges creates a distinctive climate profile for New Zealand’s largest city.