MetService said the expected rainfall will not be enough to make up the large rainfall deficits in many places but it will be a good step in the right direction.
The rain is likely to be followed by a period of showers on Monday as a cooler southerly spreads over the country, before an anticyclone moves back over the country later next week.
The forecast has also sparked a warning from police and transport officials about dangerously slippery roads.
Northland police highway patrol acting manager Sergeant Lance Goulsbro said rain after a long, dry spell made the roads slippery and potentially dangerous for unsuspecting motorists.
"The roads will definitely be more greasy after rain as it brings the oil up to the surface, so it's good to remind people now that they will need to slow down and drive more carefully. It's no use telling them after it rains," Mr Goulsbro said.
He said the hot weather had also brought tar up to the surface in some places and rain on those spots could be dangerous.
"People will need to slow down and increase their gap between the vehicle in front to give themselves more time to stop if they need to," Mr Goulsbro said.
NZ Transport Agency director for Auckland and Northland, Stephen Town, said people would need to take care on wet highways and roads.
"All summer long, dust, dirt, oil and other debris builds up on the surface and when it rains, those ingredients combine and get stirred up to make driving conditions slippery and dangerous. Conditions are at the worst in the first few hours of rain, and light rain is more of a challenge than a heavy downpour."
He said one of the most common causes of a wet weather crash was driving too fast for the conditions.
