Northlanders are being warned to enjoy their swimming and beach activities this week as the weather is expected to change come the weekend.
MetService meteorologist Georgina Griffiths said the average sea temperature around Northland's coast was currently close to 17C.
She said this is about half a degree warmer than the average for this time of year.
"The sea temperatures around the Northland coastline have risen sharply over the last fortnight, due to an unusually persistent high preventing strong winds in the area."
Griffiths encouraged people to enjoy their swimming or beach activities this week because by the weekend a return to windier, more changeable weather was expected.