Drying Trend Emerging Across Parts of New Zealand as Summer Approaches

A drying trend is beginning to show across several parts of New Zealand as the country moves further into spring, with soil moisture now below normal in parts of the North Island and upper South Island.

WeatherWatch chief executive Philip Duncan reported on 11 October that the clearest drier-than-normal soil moisture conditions are currently showing in much of Northland, particularly around Whangārei, along with eastern Bay of Plenty, East Cape, Gisborne and Tasman.

Several neighbouring regions are also beginning to lean drier, including much of the Bay of Plenty, Waikato, Taranaki, Whanganui, Manawatū-Horowhenua and Nelson.

Importantly, Duncan said none of these areas are currently alarmingly dry. The significance is the direction conditions are moving as New Zealand heads towards summer.

High Pressure Is Beginning to Reduce Rainfall

The change follows a shift towards more dominant high-pressure systems.

Rainfall over the past couple of weeks has been particularly limited in western Northland, Nelson and Tasman, and eastern Bay of Plenty. October has also started relatively dry in parts of Otago, Canterbury, Tasman, Taranaki and Northland.

Earlier this month, Duncan warned that the drier phase associated with the current El Niño pattern appeared to be arriving as high pressure increasingly restricted rainfall across much of the country.

Earth Sciences New Zealand has also forecast a drier-than-normal spring for northern and eastern parts of the country, particularly northern and eastern areas of the North Island.

The Picture Is Very Different in the South

The drying trend is not nationwide.

Soil moisture remains higher than normal across much of the eastern South Island from around the Taieri Plain north to Blenheim, with Christchurch itself an exception.

Coastal Canterbury and Marlborough have also received above-normal rainfall recently, while Southland has experienced a particularly wet end to winter and start to spring.

That regional contrast is typical of New Zealand during El Niño, when stronger westerly weather patterns can produce much wetter conditions in some areas while increasing dryness elsewhere.

What Does This Mean for NZ Gardeners?

For home gardeners, the current conditions are not a reason for concern, but they are worth watching.

Spring gardens are now entering a period of rapid growth, and increasing temperatures, longer daylight hours and stronger winds can cause soil moisture to decline quickly when rainfall becomes less frequent.

Gardeners in regions already trending drier may want to begin checking moisture below the soil surface, particularly around newly planted trees, shrubs, vegetables and container plants.

Mulching while soil still contains good moisture can also help reduce evaporation before hotter summer conditions arrive.

There is little benefit in waiting until plants are visibly wilting before responding to drying soil.

A Trend Worth Watching

Forecasts indicate high pressure is likely to remain an important feature of New Zealand's weather through October, although individual rain events will continue to interrupt the overall pattern.

With El Niño expected to remain a major influence through the coming summer, soil moisture will be something both growers and home gardeners will need to keep an eye on over the months ahead.

For now, New Zealand is not facing widespread drought conditions — but in several regions, the first signs of the summer drying trend are beginning to appear.