If it's feeling hotter at your place than MetService is reporting, there's a good chance you're right.

While weather forecasting is indeed a science, that doesn't mean the MetService figures reported each night in your city are the same at your house - or even your part of town.

Take Auckland, for example: temperatures in the city centre have been sitting at about 26C this afternoon, and they've been around the same at North Shore and Manukau.

But out at Waitakere and Hunua, temperatures have hit 30C.


New Zealand's diverse landscape and the simple fact we're surrounded by ocean meant there would always be variations in temperature on any given day or night.

It could also be due to topography, being close to the sea, direction of slope and other influencers like the built or natural micro-environment.

"It really just comes down to geography: you don't need much of a difference in it to get different temperature readings," MetService meteorologist Tui McInnes said.

"At Kelburn, where we're based, we've been reporting 25C, but out in the Hutt, it's been 26C."

On a smaller scale, the microclimate of your back garden – and namely how exposed or sheltered it was – could even account for a degree of difference.

People also might have also noticed differences between the local highs and lows they'd checked throughout the day, and what got reported on the evening news.

Each media outlet has their own approach, depending on how focused they are on urban versus regional areas, observations versus forecasts, what timeframe constitutes a day.

That included choosing which sites they focused on, and what they did when an "outlier" site recorded the highest value.

"In other cases, it comes down to timing: daily maximum temperatures on TV were the highest temperatures so far that day, up to the time we send the information to the media outlets."

And as for how those temperatures were actually captured, most figures for most towns and cities - including Auckland, Wellington and Christchurch - are recorded at airports.

This was to offer the most accurate current conditions for aviation, and McInnes said these stations were up to the highest specifications.

Source / MetService
Source / MetService

What is the best way to get an accurate reading at home?

Ideally, thermometers needed to be about 1.3m above ground; protected from direct sunlight, rain and snow; and placed in a well exposed position, preferably four times its height away from obstructions like trees and buildings.

In most cases, where people did notice variations in temperature compared to their home thermometer, they could adjust the readings compared to what they see on metservice.com.

All temperatures measured by MetService are recorded on highly sensitive instruments in ideal locations, out of direct sunlight and away from heat sources, housed in Stephenson's screens.

But good recording spots for official stations are hard to find.

Along with the other requirements, sites have to be secure from vandalism, with reliable access to power and communication, and few obstructions - something most urban and suburban areas cannot offer.

Large parks and sports fields tend to be the best prospects - the weather station at Lumsden in Southland is located on the local high school grounds.

And all recordings are made in line with international best practice: MetService's observation network was set up in line with World Meteorological Organisation recommendations, where standard enclosures and a standard exposure are used, so temperatures are comparable from place to place and from day to day.