The MetService says the “very miserable” inversion layer is likely to persist until at least the coming weekend, in the absence of a front to “flush it out”.

The inversion is an annual weather event which results from rapid cooling at the surface under clear sky conditions, forming an inversion at low levels due to the temperature difference of the air just above the surface of the land and the air higher up.

MetService meteorologist Andrew James kindly explained it’s currently “very miserable” in the Upper Clutha. 

“Not great, not particularly warm, and typical for this time of the year to get a long spell of this kind of weather.

Roving Wānaka App reporter Scout checks the fog level. PHOTO: Wānaka App

“We are seeing signs of that continuing through to Saturday. We need to get rid of this - get something to come through and flush it out.”

Unfortunately he wasn’t seeing much change, although he said it “may break up a little bit through the weekend”.

“For now it’s looking like another few chilly days and cloudy conditions persisting in those sheltered valleys.”

This image from the Crown Range webcam shows us what we already know. IMAGE: NZ Met Service

The MetService says the lack of heating at this time of the year, when the sun’s at its weakest, combined with a lack of wind to mix dry air from above, means the moisture stays in basins and valleys.

Usually under a ridge of high pressure there are light winds and generally clear skies, which allows rapid cooling to take place at the surface, but if there’s moisture trapped at low levels that condenses into fog, which can stay trapped in these valleys for days.

People’s best bet to find some sun is to walk up a hill or head to Cardrona Alpine Resort, or Treble Cone which is scheduled to open this weekend (Saturday June 24).