September's weather has continued the 2009 trend of not conforming to the expected, hydrological consultant Dave Stewart says.
Usually in September, spring-like weather occurred, with some warm days and some cold days, with westerlies followed by southerlies and occasionally snowy conditions, he said.
Last month began that way but that all changed after September 20, Mr Stewart said.
Unusually, for the remaining days of September, easterly quarter winds dominated, due to some large weather systems crossing the North Island and north of the South Island, and those directed northeasterly to southeasterly winds and rain on to the east of the South Island.
"September continued the trend of not conforming to the expected, as has most of 2009."
Easterly quarter winds and rain were unusual for September, but it was very welcome as conditions had become very dry, he said.
Farmers were calling for more rain and warmth to boost growth through the rest of spring.
In North Otago, rainfall totals varied from no rain to a little, with most recorded in the last 10 days of the month.
Total falls at the indicator sites (average monthly totals in brackets) were:Waikoura 58mm (36mm), 62% above average; Oamaru Airport 31mm (23mm), 34% above average; Oamaru Town 51mm (32mm), 57% above average; Kauru, the Dasher 89mm (34mm), 161% above average; Palmerston 70mm (34mm), 107% above average.
Significant falls during the month were: September 24-25, Waikoura 31mm, the Dasher 44mm, Palmerston 35mm; and September 28-29, Oamaru Town 21mm, the Dasher 25mm, Palmerston 25mm.
Monthly river flows were close to, or above, their long-term averages for the month. Flows were reasonably steady for the first 20 days, probably due to snowmelt, but in the last eight days, rivers rose and the Kakanui recorded a rise of about 1m on September 26, he said.
Farmers reported rainfall at the end of the month restored soil moisture levels to the stage that lack of moisture was not an issue for growth, but the colder conditions were a factor.
In Central Otago, rainfall ranged from only 4mm (Hills Creek) to 20mm (Cromwell).
The easterly quarter winds were not vigorous enough to spread rain very far inland, Mr Stewart said.
Total falls were:Lindis Crossing 20mm (38mm), 49% below average; Cromwell 20mm (16mm), 24% above average; Alexandra 11mm (18mm), 39% below average; Merino Ridges 11mm (24mm), 54% below average; Ranfurly 4mm (24mm), 82% below average; Tima 13mm (43mm), 71% below average;Average monthly river flows were below their long-term averages for September.
The rivers began the month with good flows in them but flows steadily declined through lack of rain and through increasing irrigation abstraction.
Farmers reported some growth during the month but lack of moisture on non-irrigated land was becoming an issue and slowing growth.
In Lakes Wanaka, Wakatipu and Hawea and surrounding areas, rainfall totals were much lower in September than in August.
Total falls were:Makarora Station 110mm (235mm), 53% below average; Hunter Valley Station 17mm (93mm), 81% below average; Glenfinnan 83mm (202mm), 58% below average; Hawea Flat 11mm (61mm), 83% below average; Queenstown 38mm (70mm), 45% below average.
Other rain gauge totals included Halfway Bay 50mm, Arthurs Point 35mm.
Significant fallsincluded: September 1, Glenfinnan 17mm, Queenstown 18mm; September 10-11, Makarora 35mm, Glenfinnan 21mm, Routeburn 21mm; and September 18, Routeburn 23mm.
River flows were generally close to or below their long-term averages for September.
In many rivers, flows declined slowly as the month progressed.
Levels in Lakes Wanaka and Wakatipu began the month at 278.16m and 310.28m, 1.1m and 0.45m above average, respectively.
Both lakes fell steadily throughout the month to end September at 277.11m and 309.84m, both very close to average.
Lake Hawea began the month at 342.13m and rose steadily for the first 18 days of the month as outflows were at their minimum.
It reached 342.72m on September 21 but fell slowly after that as Contact Energy increased the outflows.
At the end of September, the level was 342.61m, 3.4m below full.
Farmers reported there had been some grass growth through the month, he said.
"In the lakes headwaters, there has been sufficient rain to maintain growth.
But further down the lakes, conditions were getting very dry and rain is needed to ease the dry conditions."
In Strath Taieri, Lower Taieri and Dunedin, rainfall was generally close to average.
Most of the rain at all sites occurred in the last 10 days of September.
Total falls were:Garthmyl Middlemarch 32mm (27mm), 20% above average; Musselburgh Dunedin 46mm (49mm), 5% below average; Lee Flat 42mm (50mm), 16% below average; Maungatua 51mm (55mm), 7% below average; Dunedin Airport 38mm (40mm), 6% below average; Pine Hill 70mm (52mm), 34% above average.
Other rain gauge totals included Ross Creek 69mm, Southern Water Treatment Plant 48mm, Sullivans Dam 97mm.
Significant falls included: September 28, Dunedin Airport 17mm, Musselburgh 28mm, Maungatua 17mm and Pine Hill 28mm.
River flows were generally below their long-term averages for the month.
They all showed a general decline from the beginning of September until the easterly quarter rains began around September 21.
Flows slowly rose after that.
Farmers reported a reasonable month for growth but the rain in the last 10 days was very welcome, he said.
In South and West Otago, rainfall totals ranged from 21mm (Moa Flat) to 76mm (Slopedown).
Total falls were: Tuapeka Mouth 42mm (42mm), average; Balclutha 57mm (38mm), 49% above average; Waikoikoi 40mm (56mm), 28% below average; Slopedown 76mm (113mm), 33% below average; Moa Flat 21mm (51mm), 59% below average; Clarks Flat 40mm (50mm), 20% below average;Significant falls during the month included: September 1-2, Tuapeka Mouth 15mm, Balclutha 23mm, Waikoikoi 17mm, Slopedown 35mm; and September 28-29, Balclutha 23mm, Slopedown 15mm, Clarks Flat 15mm.
Apart from the Clutha, average monthly flows were below their long-term averages for September.
The Clutha was above average due mainly to above average outflows from Lakes Wanaka and Wakatipu.
Farmers reported a reasonable month with good growth in some areas.
