Understanding the pattern
The main weather pattern this weekend is a contrast between calm northern seas and far rougher conditions down south. A steady ridge sits firmly across the North Island, keeping skies mostly clear from Northland to Wellington. In the South Island, things are livelier. A strong system pushes into Fiordland and Southland late today and tomorrow, carrying gale winds, bursts of heavy rain, and large ocean swell.
On Monday the front weakens as it reaches the upper South Island. It loses much of its strength once it runs into the ridge that continues to shelter northern regions. By Tuesday most of the country sits under settled pressure once again, though another weather push is already lining up to clip Fiordland later that day.
It is classic early summer patterning. The north feels warm and settled while the far south continues to deal with leftover winter energy moving up from the Southern Ocean.
Regional outlook in detail
Castlepoint
Northwest winds remain fairly solid today with gusts near gale strength at first before easing back. Seas are rough this morning though conditions improve later in the day. A long period southwest swell arrives this afternoon and will be noticeable for smaller boats.
Sunday stays northwest but at more manageable levels around 25 knots, easing further north of Cape Palliser by evening. Swell drops away which will suit anyone launching early and coming home late.
Puysegur point
Puysegur point, down South, is the weather hotspot this weekend. Winds swing through northerly into northwest and reach 45 knots by early evening today. Seas climb into the high range for a time with a four metre westerly swell running through. Heavy rain lowers visibility from evening.
Sunday keeps the northwest theme with winds near 40 knots before easing at night. Very rough seas and a heavy northwest swell continue. Not a weekend for venturing offshore.
Wellington
Wellington holds a steady northerly through the weekend. Today starts with 25 knots gusting 35 knots before a short break in the afternoon, then returns to similar strength tonight. Seas ease briefly before picking up again with the evening breeze.
Tomorrow brings a more even day with northerlies around 25 knots and clearing skies. Swell stays low on the South Coast while Castlepoint keeps a leftover southwest metre early on.
Broader picture
Northland to Taranaki
Mostly fine with light winds under the ridge. A few afternoon showers north of Whangarei. Good conditions for diving, fishing and cruising close inshore.
Coromandel, Bay of Plenty, and the central high country
Fine for most. Gisborne and Wairoa districts may see afternoon showers with the chance of thunder and hail. Seas stay moderate and winds are gentle across the region.
West Coast from Buller to Fiordland
Cloud thickens today with rain building north of Hokitika and spreading south. The heaviest falls arrive tonight and tomorrow. Swell rises steadily from the west and may be uncomfortable for smaller craft.
Nelson, Marlborough and Canterbury
Fine with increasing high cloud. Isolated inland showers this afternoon. Winds stay light through Sunday though the next wave of rain approaches Monday.
Otago and Southland
Morning showers clear coastal areas before returning late in the day as the front moves closer. Sunday brings rain in the west and a stronger northwest flow across exposed water.
Looking ahead
Sunday continues the split pattern. The North Island enjoys a run of fine weather while the lower South Island faces heavy rain and strong winds. Monday sees the rain band push north up the West Coast before weakening as it moves into Canterbury and Marlborough.
Tuesday offers a calmer day nationwide with the ridge back in control, though another front edges toward Fiordland late in the afternoon. Wednesday sees that weaker front sliding up the South Island while the North Island stays settled.
For boaties, the message is simple. Northern waters offer an inviting stretch of early summer conditions. The lower South Island should expect several days of rugged weather before things settle again from mid week.
Weather information from New Zealand METservice.
