The Waikato region and Ruapehu District have been classed as medium-level drought zones.
This is the fourth year in a row that the regions have either been in drought or have experienced extremely dry conditions.
Agriculture Minister David Carter made the announcement on Wednesday morning during a visit to farms west of Hamilton.
Mr Carter says droughts take many years to rebuild from and their effects are felt throughout the country.
"We've got a lot of New Zealand now very dry for this time of year, so who knows where it might end up, but we might find that the national economy is again affected by drought."
Mr Carter says the 2007-8 drought stripped nearly $3 billion from the economy.
The declaration steps up funding for local Rural Support Trusts to assist farming communities.
Northland and North Auckland are already officially in drought.
The Waikato region, along with some other parched parts of the North Island, received some rain on Tuesday but rural support trust chair Neil Bateup says it was far from enough to make any difference to the soil moisture deficit.
There's also been rain in Northland, but farmers say there say it will do little to alleviate drought conditions.