Muggy, sticky, humid heat - for most Aucklanders yesterday the city would have felt like being trapped in a Turkish bath.

Last night wasn't expected to be much better with experts predicting some parts of the city were in for the second muggy night in a row.

MetService meteorologist Bob McDavitt said the minimum temperature recorded at Whenuapai on Monday night was 20C, a record for that area at this time of the year.

The same kind of temperature was expected last night but the humidity would hopefully reduce a bit today when a southwesterly kicks in, blowing away the warm subtropical air that has been leaving people in a sweat.

Humidity levels varied around the country yesterday, but in Auckland a high "dew point" reading left many with a day they would sooner forget.

Mr McDavitt said the dew point measures how saturated the air is with water.

"The higher the dew point, the muggier you feel. Auckland had a dew point of 21 degrees and anything higher than 20 degrees means that more than half of the population will be feeling uncomfortable and too hot."

He said it was too muggy yesterday for people to cool down the way their bodies are designed to.

"Human [sweat] is supposed to evaporate which makes a nice cooling effect to keep the body comfortable.

"However, when it can no longer evaporate because the air's so thick with water and the dew point is so high, it becomes very uncomfortable."

Heavy downpours in the CBD yesterday also helped add to the feeling the city was one big sauna.

New Zealand is now experiencing a change in weather patterns which means many areas across the country will get more than 10mm of rain this weekend. This will be welcome news to farmers - especially in Whangarei which has not seen more than 10mm of rain for two months.

"There are more fronts and troughs of low pressure predicted to move across New Zealand from the Tasman Sea this week and next week, with fewer days affected by the dry highs which we have become accustomed to over the past six weeks."