The National Institute of Water and Atmospheric Research has said soil moisture levels are "incredibly dry" for this time of the year, although the Ministry for Primary Industries has yet to declare a drought.
Northern fire communications shift manager Jaron Phillips said people had lit many fires across Auckland during the weekend despite a complete fire ban declared by Auckland Council.
All open-air fires, including rubbish fires, bonfires, backyard braziers, fireworks and cooking fires, are banned.
There were 17 as a result of backyard rubbish burns; one from a cooking fire; one from a brazier fire; two from bonfires lit on the foreshore; and five started by fireworks.
In Wiri, a hangi set a fence on fire. Elsewhere, a brazier was knocked over and ignited vegetation.
"It's apparent that lots of people aren't aware of the fire ban so they are continuing having backyard fires, setting off fireworks, having hangi and umu and using braziers," Mr Phillips said.
Gas barbecues could be used, but not those that used solid fuel such as charcoal or those with an open flame.
Council spokeswoman Sharne Parsons said it was likely many of the people breaching the ban were not aware of it.
Meanwhile, principal rural fire officer Bryan Cartelle said a blaze that destroyed more than 100ha of bush on Great Barrier Island had been contained.
Firefighters were continuing to dampen hotspots.
Aucklanders used 2.84 billion litres of water in the past week, down from 2.95 billion litres the week before.
Water levels at Watercare's dams
Yesterday: 81.7 per cent
Previous Friday: 83.9 per cent
Average for this time of year: 85 per cent
Rainfall at dams
Waitakere Ranges
Last 7 days: 15mm
Month to date: 24mm
Historical monthly average: 100mm
Hunua Ranges
Last 7 days: 6mm
Month to date: 7mm
Historical monthly average: 105mm
Source: Watercare.