The drought in Northland would cover the whole region, as well as parts of Auckland north of the harbour bridge.
It would enable emergency financial support for farmers who had lost their incomes, which Federated Farmers expects could apply to about 20 families in the region.
Northland Rural Support Trust co-ordinator Julie Jonker said most areas in Northland had been without rain, and none was forecast for the next fortnight.
She said milk production had fallen rapidly as farmers moved to once-a-day milking.
The last official droughts in the region were declared in January and December 2010.
WeatherWatch head weather analyst Philip Duncan said a number of regions of the North Island had reached the tipping point of drought criteria, with the north and east the most badly affected.
"It's really the North Island that's having a tougher time this year because it isn't as well equipped for dry weather as much of the east of the South Island is."
The rain had failed to come because of a big high over the country - and the next possibility of rain was almost two weeks from now, when there was a chance of a subtropical low.
"We're hoping it will bring rain to the north and the east especially of the North Island."
But Mr Duncan said there was still a risk the low could come down the wrong coastline, which meant the rain could be even further away.
"A lot rides on this chance of rain because if this low fails, that could cause some significant issues for the dairy farming sector in particular.
"But it's still too early to be getting too grim about it, because summer weather usually lasts until mid to late March." Prime Minister John Key yesterday said the Government was keeping a close eye on the situation.
He said one of the big risks was that people's livelihoods were tied up in their farms.
"Through weather conditions they can't control, their livelihood is severely challenged and that can be very depressing for people. We just try and make sure there's an outreach programme of support so they don't feel isolated and lonely."
Waikato Regional Council chairman Peter Buckley said the situation had been getting more critical since its drought committee met late last week.
Farmers had been coping reasonably well, but something needed to be done as it got more serious.