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ClimateWatch: March sees La Nina continue to fade (+11 Maps + Video)

March is here and now the Autumn weather pattern will continue to expand as summer weather continues on for some, but increasingly shows signs of fading.

The tropics will be very busy for the first 10 days of the month north of NZ with several lows developing. This will make for very high rainfall accumulations (200 to 300mm) north of New Caledonia, especially as a tropical cyclone will likely form in the Coral Sea area this week and then track east to south eastwards (towards New Caledonia) during Week 2.

Sea surface temperatures. It’s above 30 degrees (off the key, which is a NZ based key!) in the Coral Sea area now, which is where a cyclone is likely to form this week and grow/move next week.
Click here for interactive sea temperature maps.
Highest risk for a cyclone in the next two weeks is around March 9. Based on this map, high pressure in the Tasman Sea protects NZ from a hit. One to watch.

South of NZ is about to get very stormy again. For those who followed our January update we were talking about how stormy the Southern Ocean was, with not just large lows but powerful low air pressure too. In February that all eased. But March looks similar to January with some big storms in the Southern Ocean injecting more windy westerlies into the South Island and lower North Island, along with some colder southerly changes.


Lows are marked with blue boxes. Highs are marked with red boxes.
Week 1: This map shows the tropics very busy in Week 1 of March. The Tasman Sea is also seeing low pressure.
Week 2 shows a cyclone forming in the Coral Sea (east of Queensland) along with a series of lows stretching eastwards over the tropical islands, including Tonga/Fiji area. The Southern Ocean has 3 powerful storms in it.
Week 3: A very large low south of Australia and NZ dominates this map. So too does high pressure north of NZ, blocking any tropical life and keeping northern NZ fairly dry. Speaking of tropical life – the tropics look much quieter as we go through Week 3 of March.

Scientists we trust at Australia’s Bureau of Meteorology (BoM) have their next main climate update on Tuesday March 2. As of this update they have been consistent for many months forecasting La Nina would be a moderately short lived event this time around. BoM’s accuracy continues on with this event.


Next 7 days Departure from Normal.
Red = Drier than average. White = Normal rainfall. Blue: Wetter than usual.
The eastern side of NZ looks driest, especially Canterbury. But many western areas return to normal rainfall, or even a little above normal for Week 1 of March.
Data with many thanks to the US Govt as NIWA in NZ won’t share this data.
2 Weeks Rainfall Accumulation (GFS model). Shows eastern and northern NZ still leaning drier – but some heavier showers may help the western and central North Island. The South Island has over 200mm of rain coming on the West Coast, but just 10 to 20mm in Canterbury.
NZ leans drier than average in most regions, especially the eastern South Island and the entire North Island.

Despite some colder injections (especially the end of Week 1 of March and first weekend) the month ahead still leans warmer than average.

This monthly ClimateWatch report is brought to you by and IBM, in conjunction with


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