A strong wind watch also remains in place from 1am tomorrow until 8am.
O’Connor said the midweek may bring calmer weather but the long weekend could be a damp one.
“While the rain will be welcome to some, it’s also falling on harder ground, which can also have knock-on effects.”
There was a risk of flooding, especially as thunderstorms were expected to hit in localised areas, she said.
Tuesday’s thunderstorms may bring between 25-60mm of rain in an hour, O’Connor said
Forecast strong winds could batter the eastern parts of Northland, particularly Paihia or Whangārei.
O’Connor encouraged people to secure items such as boats, trampolines and outdoor furniture.
She said the weather would settle through the midweek but conditions could change moving into Friday.
Another low-pressure system was forming in the Tasman Sea toward the end of the week, which could bring humid conditions and rain.
“Early indications suggest there could potentially be some rain,” O’Connor said.
“It does look like Sunday could be a wet one across most of the North Island.
“Have a think about where you’re going, or make sure you’re prepared for wet weather.”
The rainmaker comes following a dry start to the year in Northland which kept firefighters busy.
Fire and Emergency New Zealand crews battled a 20ha blaze on January 9, which took two days to bring under control.
Around 40 members battled the blaze, which was contained after three days.
The fire started as a vegetation rubbish burn which escaped.
Brodie Stone covers crime and emergency for the Northern Advocate. She has spent most of her life in Whangārei and is passionate about delving into issues that matter to Northlanders and beyond.