Auckland's prevailing wind is south-westerly, often fresh and gusty in winter and spring. In settled summer weather a sea breeze usually builds in from the Hauraki Gulf during the late morning or early afternoon and dies away towards evening.
Auckland lies on a narrow isthmus between two harbours, the Waitematā to the east and the Manukau to the west, with weather systems arriving mostly from the Tasman Sea. That gives it a varied wind pattern.
Prevailing winds. The most common wind is from the south-west. Westerlies and south-westerlies are typical behind cold fronts, particularly in winter and spring, and over the land they become gusty and shifty, with sudden strong puffs coming down off the hills and the city. Spring is usually the windiest season.
North-easterlies are more common in summer, and with a deep low to the north, or an ex-tropical cyclone in late summer, they can become strong and bring rain. A north-easterly blows straight in from the Gulf and can raise a short, steep sea in the outer harbour.
The sea breeze. On a settled summer day, with light winds in the morning, the land warms faster than the sea. Air rises over the land, and cooler air flows in off the Gulf to replace it. On the Waitematā the sea breeze typically fills in from late morning, usually from somewhere between north-east and east, strengthens through the afternoon, often to 10 to 15 knots, and fades towards evening. A light morning breeze from another direction may die away first, leaving a calm before the sea breeze arrives.
Local effects worth knowing:
- the wind bends and funnels around headlands such as North Head, and under and around the Harbour Bridge;
- it is lighter and fluky close to the city waterfront and in the lee of the land;
- wind against tide in the harbour entrance makes a choppy sea.
Always check the marine forecast for the area before going out, not just the city forecast, and look at the forecast for the afternoon as well as the morning: the wind is often stronger later in the day.
More in the book: Chapter 10, When the wind gets up