Soil moisture levels around New Zealand are, generally speaking, smack bang where they should be for this time of year. In mid-August most regions should be wet underfoot – but not necessarily hearing squelches when you walk on the ground, or having large areas of ponding or puddles.
There are some parts of NZ that are a bit muddy, but there should be far larger areas that aren’t that wet.
According to the Crown’s soil moisture maps, instead of being at field capacity (puddles on the grass, large muddy areas), a majority of the nation is at about 50% soil moisture storage. Hawke’s Bay, Coastal Otago, South Westland, the very eastern coastal side of Marlborough and parts of Northland all fare a little wetter.
But it’s Canterbury that is driest compared to usual for mid-August.
Usually in the depths of the darkest days of winter farmers around NZ, especially in the south, don’t want much rain. This year we’ve had farmers from Canterbury (and other regions) ask if more rain is coming. The concern isn’t so much directly for today – it’s about what is going to happen once spring arrives.
Usually in spring NZ gets the traditional westerlies blowing through – and this creates a bigger rain shadow for those in the east, thanks to our mountains and ranges. In other words, spring isn’t often the best season to drive rain into eastern areas. Parts of Canterbury are now well below where they should be from a soil moisture point of view.
It’s also worth noting the lack of rain falling on the West Coast, especially the northern half or pushing deeper into the mountains; this will also limit rainfall spillover into lakes and other waterways.
There have been some good snow events this winter, to help in spring when that melts, but it’s not as big as some might think despite the snowy snaps we’ve occasionally seen.
At the time of writing this the forecast for every region in NZ was to lean drier than average for next week up to about Friday, and that included some rain falling in the forecast.
Even if we look at the rainfall forecast for next week, there is not a huge amount of rain coming specifically for Canterbury. The best chances may be next weekend (August 17 and 18) for rain on the West Coast and some spillover to the east.
The long-range forecast taking us closer to the end of August shows some very big high-pressure zones moving through (especially this coming week) but there is still variety in the weather pattern and we do see low-pressure zones and cold fronts still coming into the country.
It’s not all dry. This long-range guidance suggests most rain will lean to the western side of NZ, and that we still have some very large areas of high pressure to come through just yet. We remain in a neutral weather pattern – likely for the rest of this year.
