Surprise! More rare clouds over Hawke's Bay

Rare mammatus clouds at Atea a Rangi at Awatoto Napier. Photo / Paul Taylor

More rare clouds have formed in Hawke's Bay skies.

The region was treated to the rare Mammatus clouds on Saturday, and then again on Monday.

MetService forecaster Cameron Coutts said it was rare for them to form once, but for them to form twice in such a short space of time in the same area was even more unusual.

The Mammatus clouds are caused by downdrafts, which is downwards moving air.

The lower atmosphere has to be dry for them to be visible.

They are commonly associated with thunderstorms, which is what caused their appearance yesterday.