O’Connor said an area of low pressure just to the northwest of Northland was bringing rain with it early this week.
“There’s a couple of fronts spiralling around into it and some of these bands of rain are moving southwards over Northland.
“The low system does sort of move slightly further south and west away, but a second one forms.”
There was potential for the watches to be upgraded to a warning, O’Connor said.
Monday evening was expected to bring widespread heavy rain and moving into Tuesday, winds would pick up.
This could bring with it severe gales in exposed places, O’Connor said.
“Especially if you are on the east of Northland, so in Paihia or Whangārei, you may notice these winds are particularly strong.”
She encouraged people to secure items such as boats, trampolines and outdoor furniture.
The heavy rain watch also comes with a thunderstorm risk, which could bring localised downpours.
“If you are out driving, don’t be afraid to pull over if your visibility is reduced,” O’Connor said.
The weather settles through the midweek but conditions could change moving into Friday, she said.
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.
However that was an early prediction and there was potential for it to shift, she said.
Fire permits were suspended for Northland last week following dry and windy conditions triggering escaped fires across the region.
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.
Suspended fire permits were expected to be reviewed on Sunday afternoon.
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.