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Weather …. Reflections

A recent news item mentioned how low soil moisture levels were this year in the South Island, and it got me thinking about the last 2 summers here. And that led to a new section on our weather page historical data tab

As yet I haven’t figured how to make the table or the graph “live” … a nice way to spend a wet day ??

NIWA Soil Moisture Map of the South Island, May 1st .

Taken from the NIWA web site 

I’m intrigued as to how they assess moisture levels on Stewart Island, although Iris’ comments about our garden and how dry it is do support the map.

. Annual Comparison

But they are quite revealing. 2013 through 2016 shows a fairly constant 1400 mm rain over the 12 months. The old timers always told me we could expect around 56 inches (1422 mm)per year.  2016 has a slight dip, but 2017 is really low at 1044, and 2018 still 10% below average, and that due to an exceptionally wet April & May. So far this year the average for each month is more or less the same as last year.



Rain Forest

A 10% drop doesn’t seem much, but looking at the figures the summer is quite dry. Rain forest soils dry out really quickly, and the moss banks even more so, especially with higher than normal temperatures coupled with breezes. Last summer we had a fire get away from a camp site, and although restricted to a small Island in Paterson Inlet it was a good wake up for what could happen. 


Dead Punga, Ulva Island



So What Does This Mean For The Island.

Firstly I’ve noticed more dead pungas this year. And especially noticeable is that many are in areas I would have thought quite damp. But then I realised pungas need moisture in at the crown as well as the roots, as being as porous as they are they can and do dry out.
Iris tells me even after the 80+mm of rain we’ve had the last two weeks the ground is still quite dry a spade depth down. And soil temperature is 12.8 deg C. Which explains why I still have to mow our lawns every week …. sigh !!

That was quite noticeable over the summer.  I started carting water in early December, as it was shaping up to be like the previous December, and pumped 5000 litres, which equals about 25mm over all. Then we got quite a bit of rain in January and a bit less than average in February. So stopped carting. But things got very dry, as I hadn’t taken into account how warm it was.. And the impact that had on what would have otherwise been a barely adequate amount of rain. 

Sadly I don’t have historical temperature graphs, But this one for the 12 months past shows just how warm this May is compared with last

The Future

We harvest our domestic water off our roof, micro filter it and UV treat. And with 100,000 litres storage at Sails Ashore, and over 50,000 at Kowhai Lane we should be OK for domestic use at least, And although it can be a pain I can easily pump and transport garden water from a local creek. But several Island properties ran completely out last summer and the summer before. And the dry conditions do make a forest fire risk more than a bit of an issue.