A ''Blueskin blanket'' of thick fog has brought gloom to the coast north of Dunedin after clinging to the landscape for more than 10 days.

Dunedin consultant hydrologist David Stewart said it was caused by an unusually long period of northeasterly winds that created perfect conditions for fog on the east coast of the South Island.

The fog had been particularly bad in Blueskin Bay, which, according to locals, had barely seen the sun in the past 11 days.

Blueskin Nurseries owner Clare Brown said fog was not uncommon in the area and locals called the conditions the ''Blueskin blanket''.


However, having fog stick around for 11 days was unusual and probably only happened about twice a decade.

People were ready for the weather pattern to change, she said.

''I must say, when you wake up in the morning and the cloud's still there, you think 'oh no'.''

She had been living in the area for almost 40 years and recalled the fog sticking around for three weeks 10 to 15 years ago.

One positive was the blossoms and the flowering magnolia looked fantastic in the fog.

Orokonui Ecosanctuary general manager Chris Baillie said they had not seen full sun in 11 days.

''I've been at Orokonui nearly 10 years and we've never had it last this long before,'' she said. ''We've only ever had a few days at a time.''

A Warrington resident said people were being driven a little bit crazy by the constant fog.


Mr Stewart said the prolonged period of northeasterlies was caused by an anticyclone to the east of New Zealand and a series of weather systems crossing from Australia. Onshore winds and relative calm also helped create perfect conditions for fog.

Large parts of Dunedin had been draped in fog during the past two weeks as a result, and the system had affected most of the east coast of the South Island.

Those itching for a little bit of sunshine would be relieved to know the weather system was likely to ease today or tomorrow.

He was unsure why fog tended to stick around longer in Blueskin Bay.

''It just seems to trap the fog there; the fog tends to move out to sea during the day in Dunedin. It's not uncommon for them to be foggy with it sunny [in the city].''

A silver lining of the weather system was that it blocked southerly systems, resulting in unusually warm and settled weather for the start of spring.

''Farmers will have loved the weather because it's been brilliant for lambing.''

A Dunedin Airport spokeswoman said some flights were delayed because of fog yesterday morning.