Among those most drenched places were northern, central and southern Otago - receiving 335, 483 and 202 per cent of normal rain for January - along with southern Northland, northern Waikato and the Bay of Plenty, which have received around 150 per cent of usual totals.
It was a dramatically different picture in the lower North Island and the upper South Island, with meagre totals of zero and 25 per cent respectively.
Totals were also notably lacking around the North Island's East Cape (62 per cent), Hawke's Bay (58 per cent), northern Canterbury, (51 per cent) and Christchurch (33 per cent).
"It's really been a scattershot month of rainfall," he said.
"Another interesting observation is that we saw another major flooding event this month, making it the third one in as many months."
Noll said those three big deluges which hit Napier in November, Plimmerton in December and central Otago this month could be associated with the presence of an oddball climate driver.
A moderate-strength La Nina climate system was having a clear influence on our summer weather - but this year, it was behaving markedly out of step with traditional patterns.
Under classic La Nina conditions, the north and east of New Zealand would be much wetter right now, given its tradition of bringing northeasterly storms and rain to those places, and dryness to the south and southwest.
Instead, northern areas were currently abnormally dry - the tip of the North Island was now classified as in severe meteorological drought - while fire danger in the south and southwest ranged from low to moderate.
Added to this unusual picture was the "destructive interference" to La Nina's classic flavour of a separate natural phenomenon.
That was the Madden-Julian oscillation (MJO) - a system that forms the largest element of the intra-seasonal variability in the tropical atmosphere.
"So, we've seen through January, La Nina and other forcing patterns such as the MJO basically paddling in opposite directions," he said.
"That makes it hard to tell which one will dominate our weather patterns - and what we're left with is this mixed bag of conditions all over the country.
"Trying to summarise that picture can be very difficult, so, put simply, be nice to your local weather forecaster."
Noll said there was potential for summer to take another interesting turn, with a possible spike in tropical cyclone activity in the southwest Pacific in late January and early February.
"And while there's an increased chance for activity, where that all goes in the broader region is the million-dollar question," he said.
"The overall picture here is we need to be aware, and maybe even on alert, for that kind of activity to start up here after a bit of a lull through the middle part of summer."
Niwa's outlook for January to March predicted air temperatures were most likely to be hotter than normal in all regions.
They'd be interspersed with periods of brief but highly unsettled weather, with near to above normal chances of rainfall everywhere except for the west of the South Island.
More mugginess was in store too, with spells of high humidity expected from time to time - especially in the north.
