So, you have a brand new weather station and you are setting it up; do you choose true North - the direction marked as North on our maps, or magnetic north - the direction to the Earth's pole. Depending on where you live ranging from a magnetic declination of +18° in Kaitaia to +26° in Invercargill. Take a look at  https://www.magnetic-declination.com/ for the value in your city.

Wind direction is most commonly quoted in True North terms, so we recommend using this direction. If you are using a magnetic compass, simply adjust your station orientation, or calibration by the offset at your location. If you are using the iPhone compass, you can configure it to read either magnetic or true North

This map is also quite useful: https://teara.govt.nz/en/map/9217/magnetic-declination-in-new-zealand