Now that we’ve passed the Equinox it means our days will become shorter than the nights. With warm days and long, dark nights, you tend to get a better recipe for making cloud and fog.

On top of the mild conditions and increasing darkness at night we also have calm conditions and higher humidity – all thanks to a large high that is still somewhat covering NZ but is centered well out to our east, over the Pacific Ocean.

This placement means the high is very gently bringing warmer, more humid, sub-tropical air to many places. When it’s calm, fog forms – especially as temperatures drop from the longer, darker, nights.

Fog is simply cloud that forms at ground level and like clouds in the sky we can’t always predict each and every one – but we can give general risks.

So expect more morning cloud and fog overnight tonight and Sunday – the areas with dark blue in the map below have the lightest winds and therefore a higher chance of fog and cloud formation. However the much warmer than average temperatures by day means any fog and cloud will burn off by mid morning for most who have it.

Sometimes, foggy cloudy mornings can lead to sunny, mild, afternoons but with cloud build ups that may also produce isolated downpours. This is possible around the upper North Island but is looking fairly isolated.

7AM SUNDAY WIND MAP: Dark blue indicates calm and most likely to have fog or cloud first thing. 

– WeatherWatch.co.nz