For most of us the start of daylight saving means changing oven clocks and perhaps some mild complaining about an hour's lost sleep.

But if you're Caine Varley and Roger Parsons it means a morning's hard labour recalibrating Whangarei's sundial, shifting 12 45-kilogram plates embedded in the Town Basin tiles.

Overnight tonight, 2am Sunday becomes 3am.

The Whangarei District Council-employed Mr Parsons and Mr Varley have done the sundial job about four times.

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"It helps when it's a sunny day," Mr Parsons said. "Once when we did it on a cloudy day, we started moving them the wrong way."

"When the time springs forward, you've got to move the discs backwards [anticlockwise]."

The Town Basin sundial is believed to be the biggest in the Southern Hemisphere, with a 22-metre hand donated by Culham Engineering, said Claphams Clock Museum's Sarah Archer.

Luckily, the museum did not have to change its clocks.

"We have about 1500 clocks, but they aren't set to time. We have it so they all go off at different times," she said.

Northland's 157 tsunami sirens will also be tested this Sunday, the regional council advised. The tsunami sirens are from Mangawhai to Te Hapua on the east coast and Ruawai to Waipapakauri Ramp on the west coast.

Testing will be done at 9.20am for 10 minutes and again at 10am for 30 seconds.

Daylight saving has also been a traditional reminder to check smoke alarm batteries, and make sure you have enough alarms installed.

The New Zealand Fire Service attends more than 3500 house fires each year, and in 80 per cent of fatal fires smoke alarms are either not installed or not working.

Astronomer George Hudson is the earliest known proponent of daylight saving in New Zealand. But he was ridiculed when he presented the idea to Wellington's Philosophical Society in 1895.

Parliamentarian Sir Thomas Sidey raised the idea again in 1909, but it took 18 years to convince the majority in Parliament.

Debate against his proposed Summer Time Act centred on the impact on rural people, particularly women. Opponents said: "[The bill] does not make the case for now requiring the wife of the working-man to get up an hour earlier in order to get her husband away to his work."

Mr Sidney told Parliament in 1926 that "the extra hour of daylight ... is of especial value to indoor workers as it gives one additional hour for recreation of all kinds, whether playing games or working in garden plots".

"There will be a saving in the consumption of artificial light."

The Summer Time Act passed in 1927 and authorised the advancement of clocks by one hour between November 6, 1927 and March 4, 1928.

This time round, Kiwis claim back their lost hour on April 2, 2017, when 3am becomes 2am.