Whatever The Weather
Summer got off to a poor start in Auckland in December - and January wasn't much better, with conditions cloudier and cooler than normal.
Records revealed December was the cloudiest since records began and the theme continued in January with about three-quarters of the usual sunshine quota in January.
There were five days with virtually no sun, compared with 10 days in December.
The cloudy and cool conditions were caused by more lows east of the country producing more frequent south westerlies, with their commando raids of cold air up from the southern oceans, from time to time.
As a result, mean temperatures were a degree below the January average at 19.0C instead of the usual 20.1C. The average daily maximum was 22.3°C, and the warmest day only struggled up to 25C. The coldest night was 11C.
The feature that dominated Auckland's weather in 2011 was La Nina: this ensured a wet and mild year.
The year's highlights included a very wet January and December, winter not starting until July following a record warm June, and the cloudiest December on record.
Plentiful rain was a theme of 2011 with totals of 1540mm at Mangere and 1390mm at the airport, a jump of 25 and 15 per cent. January recorded 235mm of rain with a deluge of 91mm being recorded at Mangere on the 7th. December was not far behind with 201mm.
However, there were a couple of dry months which allowed gardens and sports grounds to dry out in February with 29mm and August with 37mm. For much of the remainder of the year, apart from a drying out in November, gardens would have received sufficient moisture.
The rain would have been a curse to those using sports grounds as they would have slipped and slid from April through to September.
La Nina visited New Zealand in full force last month bringing Auckland its cloudiest December in over 100 years of sunshine records. To make things worse, there were 10 days with virtually no sun, more than double the average rainfall and frequent days of strong to gale north easterlies that reached 65 to 75kmh at the airport and Mangere.
The very cloudy, wet and windy weather was caused by more pesky lows to the north west of Northland, and fair weather highs or anticyclones passing south of New Zealand. This projected moist north easterlies on to the top half of the North Island, which targeted Auckland.
Although conditions were apalling, mean temperatures were a tad up on the December average of 18.5 degrees Celsius, with 21.5C by day and a mild 15.1C at night. The warmest day was around 24C while the coldest night was 11 to 12C.
The northeasterlies brought with them lots of rain with totals amassing 180 to 200mm over the Auckland area. Much of the rain was spread over 12 rain days, with 70mm being amassed in the last two days of the year. Auckland Airport recorded 185mm of rain, 210 percent more then normal.
As a result of the downpours, and with soils being warm, gardeners would have faced rampant growth of their greens and moisture-loving plants. Although soils were drying at the beginning of the month, the frequent heavy rainfall brought soil moisture almost back to full capacity, so no watering of gardens has been required at all. The lawns would have required regular mowing as grass loves these conditions. Summer crops such as tomatoes and peppers would have received a check with the lack of sunshine.
In November the soil continues warming and gardeners who planted their summer veggie plots with tomatoes, peppers and cucumbers will notice that these start to move. Summer annuals such as petunias make good progress. This November 2011 has been close to average allowing growth to progress well.
The mean temperature for Auckland was up 1°C on October averaging 16 to 16.5°C, close to normal. The coldest night was 9°C, with the warmest day about 24°C.
More south westerly winds prevailed than usual. They typically produce cloudy showery weather in Auckland. Showers are much more frequent in the wetter parts of the region, especially in the hilly areas of the Hunua and Waitakere Ranges, where rainfall is about double that of downtown Auckland. However the showers are often light, and do not amount to much rainfall, which was the case in November. But it means it’s been another month when lawnmowers would have been busy.
Rainfall was well down for the month with Auckland Airport recording 50mm, 26mm less than the usual quota, so soils have started drying out for the summer. At this time of year about 3 mm per day is lost through evapotranspiration to the air, so the soil would have lost some moisture storage – not yet dry enough where watering is required, but enough to start checking growth slightly. In November with the evapotranspiration loss of about 90mm, and the rainfall gain of 50mm means that soils would have been depleted by 40mm.
The cloudiness of October continued with 181 hours of bright sunshine in November – the norm is 200 hours. South westerlies usually are dry and cloudy which was the character of November. This has been caused by more anticyclones located in the Tasman Sea and lows to the east of New Zealand projecting winds from the south west over the Auckland region.
October is the month in Auckland when the soil warms up and gardeners can plant up their summer veggie plots with tomatoes, peppers and cucumbers. Flower gardeners can pop in those very colourful summer annuals such as petunias, and the summer lilies start to sprout. So how has October 2011 been for the City of Sails?
The mean temperature for Auckland has been about 15.1 degrees Celcius, which is just over half a degree above average. So overall days have been quite mild, and nights warm for the time of year. The coldest night has been around 9C, with the warmest day about 22C so far, with no significant cold spells. So these mild conditions have been ideal to give the summer crops and flowers the warmth they need to get growing. The downside of course is that lawn mowing has been much more active than usual.
Rainfall has been running slightly above average for the month. Auckland Airport has recorded 109mm and Mangere 119mm, with the heaviest fall being around 20mm in one dollop. This has been sufficient to keep gardens moist without gardeners having to irrigate lawns or crops. At this time of year about 3mm per day is lost through evapotranspiration to the air. This is a combination of evaporation from the soil surface. Plants also 'breathe out' moisture through their leaves - a process called transpiration. The soil has a store of water - depending on the soil type of between 100 and 150mm. In October with the evapotranspiration loss of about 90mm, and the rainfall gain of 110-120mm means that soils have been able to replenish their moisture supply by 20mm, keeping soil moisture levels nicely topped up for growth.
It has been a tad cloudier than normal with 159 hours of bright sunshine recorded in the first 30 days of the month. The monthly quota is up around 200 hours for the month of October. This has been caused by more anticyclones to the east and south of the South Island resulting in more winds from the north east over the Auckland region.
And what are the prospects for November? In a La Niña climate pattern more north easterlies normally occur. These bring warmer than normal temperatures to Auckland - mean temperatures averaging around 17C with 21C by day and 13C by night. Rainfall patterns are uncertain but could be average or above average. The amount of sunshine is uncertain.
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