The story of summer 2012/13 was rain, or rather the lack of it. Drought was declared for the North of the country on the 27th February, shortly followed by the rest of the North Island and parts of the South Island.

The prolonged dry spell was due to presence of large lingering areas of high pressure that dominated the weather across New Zealand. These areas of high pressure acted as blocks, sitting over the country while areas of low pressure, and their associated rainfall, skirted either side of the country. There’s more about the nuts and bolts of this here.

Figure 1: Rainfall December 2012 to March 2013 compared with normal.

Figure 1 shows a comparison of observed rainfall with average monthly precipitation, for a number of cities,  between December 2012 and March 2013.

While a few stations recorded above average rainfall during some of the summer months, the general trend for summer, including March,  was for rainfall totals to be less than normal. For example, in January this year there was only 9.2mm of rainfall reported at Auckland Airport; the January average is 71mm. Between January and March only 79mm of rainfall was reported at Hamilton, which is just a little above the average for January alone.

When we did have rainfall it mainly came along as bands pushing across the country from west to east. Because of this, the likes of Dunedin, Christchurch and Gisborne on the east coast received very little.

Looking at the averages alone can sometimes be misleading – take,  for example, the rainfall in Wellington. Looking back at Figure 1 we can see that rainfall totals in January, February and March all appear to be around average for the time of the year (75mm in January (116% of average), 54mm in February (105%) and 70mm in March (97%)).  However, when looking at the distribution of the rain through each month (see Figure 2, below) it is clear that much of each month’s  rain fell in a day or two. There was a 32 day period between 13 February and 17 March where no rainfall was recorded at all.

Figure 2: Daily rainfall over Wellington, January to March 2013.

The rain that arrived in the Capital on 17 March was associated with the remnants of tropical cyclone Sandra. Sandra had tracked southwards from the Coral Sea before weakening over the cooler waters of the Tasman. Although a much weaker feature by the time it arrived over New Zealand, it was enough to bring some heavy falls of rain to the west coast of the South Island and the central parts of the country. These three images show the rainfall distribution over the country during the period.

Figure 3: Rainfall distribution March 16th to 18th 2013

As well as being one of the driest summers on record, the long periods of cloud-free sky meant it was one of the sunniest. New Plymouth recorded 928hours of sunshine in the first three months of the year, significantly more than the 686hrs expected in an average year. (Data from NIWA).

The sunny, dry conditions went hand-in-hand with some very warm temperatures. The top temperature recorded over the period was 34° C at Gisborne in March but in many spots temperatures exceeded 30° C on several days, and temperatures continued to reach into the high twenties right to the end of March. Invercargill reported a high of 27° C on the 31st of the month, 10 degrees above its March average.

25 December 2012 was also one for the record books with many places recording their warmest Christmas Day. The highest temperature recorded, 33° C was at Roxburgh. The image below shows a summary of the temperatures on Christmas Day.

There is a lot of weather tied up in New Zealand place names. The screaming northwest gales of Canterbury are celebrated with names like Windwhistle, near the Rakaia Gorge, Mount Blowhard, near Oxford, and Nervous Knob, near Castle Hill, where gusts of 240 km per hour have been measured.

Fine weather gets a mention with Sunnynook and Sunnyvale, both near Auckland. We have a Misty Peak and a Cloudy Bay and rainbows are well represented, being used to name an island, a mountain, a lake and a pass. Rain itself is harder to come by but can sometimes be found in the story that gave rise to a name.

Photo courtesy of New Zealand Geographic

Fittingly, several of these occur in rainy Fiordland. Monkey Creek, for example, commemorates a downpour that flooded a creek and washed away a surveyor’s dog, called Monkey, who fortunately made it back to camp the next day. Also in Fiordland Stick-up Creek was named by Martin’s Bay settlers, who were held up by a flood, while Mount Soaker speaks for itself.

In May 1773 James Cook laconically named Wet Jacket Arm in Dusky Sound after a storm forced an exploring party to stay out overnight. In Lieutenant Pickersgill’s words “On the 7th I went with the Pinnance to explore a Sound, expecting to get back on the same Night but was disappointed for it came on a very violent storm of Snow Hail and Thunder with a meer Hurrican of wind which confined us in a little Cove, and what was worse we had nothing to eat but a few Mussels which we gathered from the Rocks and nothing to drink but spring water; in this situation we were kept for 36 hours, quite wet and the woods so wet we could not get a bit of fire to burn and being entirely exposed to the inclemency of the weather.”

The naturalist, Forster, was rattled by the ferocity of the storm “ it seemed as if all nature was hastening to a general catastrophe … our hearts sank with apprehension lest the ship might be destroyed by the tempest and its aetherial fires, and ourselves left to perish in an unfrequented part of the world.”

There is also a storm hidden behind Cook’s naming of Hawke’s Bay. First Lord of the Admiralty, Edward Hawke, rose to fame as the only naval commander in the age of sail to initiate a battle in a full gale.  In November 1759, Hawke ordered his fleet to pursue the French as they retreated into Quiberon Bay seeking a safe harbour. The English ships crammed on so much sail in the chase that some of them sustained damage. The seas were so large that water entered some ships through their gun-ports. One of the French ships capsized and sank in a squall when this happened while the English ships managed to right themselves and shed the water.

Caught off balance by the audacity of Hawke’s attack the French Admiral never regained the initiative. The result was a crushing victory, which ended all hope the French had of transporting their large army of invasion to England. Had the English not won the war, some historians speculate that the USA might be speaking French today and not English.

There are also a host of Maori weather stories in New Zealand place names, as a trawl through A.W. Reed’s excellent Place Names of New Zealand will show. Kaihau-o-Kupe near Wanganui remembers a time when Kupe was held up by persistent westerly gales and rough water and had to “eat the wind” as he had no food with him.

Tongaporutu near Waitara translates as “driving into the south wind at night” and was given by the explorer Whatonga when he was sailing down the west coast searching for his grandfather Toi.

Upokopoito near Wanganui translates as “calabash heads”. The story goes that a red-headed chief heard that fishermen had mockingly compared him to a red gurnard. A tohunga obliged the chief by calling up a gale that swamped the fishermen, whose heads bobbing in the water looked like calabashes.

The Maori name for Wellington’s Mount Victoria is Tangitekeo, literally “the sound of the peak” as this was where the taniwha Whaitaitai screamed, a sound like the howling of the wind.

As befits a country astride the roaring forties, many names reference the wind. The Maori name for Solander Island in Fovueax Strait is Hautere, or flying wind while elsewhere there is a Hauiti, or little breeze, a Haunui, big wind or frequent wind and a Haumoana or sea wind.

Quite a few names commemorate misfortune, such as the numerous coastal features named after ships wrecked in storms: Benvenue Cliffs near Timaru; Buffalo Beach in the Coromandel and Union Bay near Auckland.

Mount Paske is named after a surveyor who lost his life in a snowstorm while Canterbury’s Jason’s Creek remembers a man who got severe frostbite cutting firewood and had both legs amputated at the knees.

Graveyard Gulley near Alexandra is named for two travellers killed in a snowstorm while Deadmans Terrace, on the Shotover River, is where eleven gold prospectors were killed in a horrendous flood.

A touch of humour is evident in The Gluepot, which occurs in Otago and Westland for places where carts were regularly bogged down after rains turned to roads to quagmires.

Among the many names bestowed during the voyage of the survey ship HMS Acheron in the 1840s was Blanket Bay in Fiordland, after a blanket of fog encountered there. Acheron made its way into several place names and was originally the name of a river in the Greek Underworld. Interestingly, some scholars believe the syllable ach goes back thousands of years further and is an Indo-european root word associated with streams that gave rise to the latin word aqua.

Perhaps the most delightful discovery in Reed’s book concerns a place on Banks Peninsula called Snefellness by a Danish whaling captain in 1840. It means a promontory surrounded by a snowfield and is now mispronounced as Snufflenose.

Lately, during this spell of fine sunny weather, there have been a lot of comments about the air temperatures we are showing on our web site, where they are measured and opinions about them. In this Blog post I will explain the reasons for the location of our weather stations. I will also offer some help about how you can get some use from the information they provide.

Early observations
The longest established weather stations are located in municipal gardens, and key places around the coast. In municipal gardens because in the late 1800s and early 1900s, meteorology was a new science and organisations like the Royal Society wanted to establish temperature and rainfall records in places that would be safe from needing to close or move. Around the coast because the weather-sensitive activity of high value at the time was coastal shipping. Lighthouse keepers and harbour authorities reported the weather conditions on a routine basis.

Puysegur Point, view to the west

The rise of aviation
During WW2, aviation became important. We needed to accommodate a rapidly growing Air Force and train the air crews. Meteorological staff or Control Tower staff made hourly weather reports, or more often as required. After WW2 there was a steep rise in the popularity of air travel and most of the airfields that were air bases used for pilot training were re-purposed to become airports and new ones were built; for example Rongotai and Mangere.

Napier Airport, NZNR, view to the east

Aerodromes often (but not always) provide ideal weather observing sites with wide open spaces that satisfy World Meteorological Organisation exposure criteria very well. The trouble though, is that while they’re perfect for meteorology, temperatures measured there can be very different from what people ‘feel’ and increasingly measure with low-cost weather stations around their towns and homes. More about this later.

Automation
During the 1980s the Ministry of Transport decided to de-man the lighthouses, but weather reports were still required, so that began the development of automated weather observations. There have been several generations of AWS (Automatic Weather Station) over the years, and that continued as the airport stations were de-manned of weather observers. Airport AWS are now quite sophisticated in that, as well as the usual meteorological elements,  they can detect up to 3 cloud layers (up to the cirrus level), measure horizontal visibility and even detect what kind of precipitation is falling – hail, snow, rain, showers, and the presence of mist or fog. Increasingly they are including webcams.

Locations for stations
Land transport and its safety concerns have led to the location of a class of weather stations for that purpose –Desert Road Summit, Arthurs Pass, Rimutaka Hill Summit are examples.

The observing network continues to grow by trying to fill in the gaps between the coastal stations and the airfields. Some stations are located in strategic places to solve a particular weather monitoring or forecasting problem – Golden Valley, Galatea, Flat Hills, Culverden, Fairlie, Roxburgh, Birchwood, Slipper Island, Le Bons Bay, are all examples of this.

Whangaparaoa, looking south

Good AWS observing sites are fairly hard to find. They need to be secure from vandalism. They need to have good unobstructed exposure for wind, rain and temperature. Access to power and communications needs to be reliable. Most urban and suburban areas are not suitable because of lack of security, or because of obstructions or poor and unrepresentative exposure for wind, rain and temperature. Large parks and sports fields are the best prospects. Ideally the station should be located in a flat grassed area with nearest obstruction 10 times its height away from the enclosure. Schools are probably worth considering. Lumsden AWS is located in the local high school grounds.

Lumsden, looking south

Aside from exposure considerations of the site, the instruments – particularly the thermometers – have to be housed in a screen. The old style screen (see the Whangaparaoa photo) is a wooden cabinet, painted flat white with louvred sides, mounted 1.25 metres above the ground. This shades the thermometers from the direct sun, and provides ventilation. Modern modular automatic weather stations have a smaller plastic “screen” to shade and ventilate the instruments. The combination of the site environment and the screen makes meteorological observations comparable (as far as possible) across the network, as well as being representative of the wider vicinity.

In some cities, the Council has provided a weather station (sometimes only a thermometer) in the central city area, and we welcome this to provide temperature information where people are going about their day to day activities. But it is essential that the thermometer gives an accurate and representative reading of the temperature of the air. Dunedin City (located at the Octagon) is a good example of this.

In other places there is a choice of weather stations. In Wellington there is an AWS at the Airport, one at Kelburn, in Lower Hutt, Wainuiomata, and Mana Island. The temperature at the Airport site is influenced by the proximity to the sea, particularly when there is a sea breeze. But is has wind exposure quite representative of many parts of the region. Kelburn is located 127 metres above sea level and because of that will, on average, be about 0.8 degrees Celsius cooler than the temperature at sea level. And there will be other influences at other places involving the local environment and characteristics of the larger scale air ventilation.

Adapting nearby data to your location
On Monday 28 January 2013, there was a light southerly wind flow over the region. The Airport was reporting temperatures around 18 to 20 degrees in the afternoon while Lower Hutt was reporting 23 to 24 degrees, and Kelburn had 24 to 25 degrees. Mana Island was reporting 17 to 18 degrees, and Wainuiomata was baking in 26 to 28 degrees. All of these are representative of their vicinity and nearby places that gave similar geography and relationship with the sea.

We show temperatures from these stations more or less in relation to their immediate suburban areas, and most of the time they will be satisfactory. Other times, when conditions are a bit unusual (height of summer, little wind not of the prevailing direction, no cloud), there are going to be significant variations around the region. We want people to make allowance for this when they are consulting our website (or mobile apps) for temperature information in relation to what they may be experiencing in their particular spot.

For Christchurch there is a choice of weather stations. Sometimes Christchurch Airport is more representative of the Eastern suburbs than New Brighton Pier. We expect people to interpret the data on our website when checking out the observations in their location.

New Developments
There are exciting developments on the horizon with weather observations. Really keen weather watchers will already be aware of web sites such as wunderground.com that collect privateer weather station data and display it in a common format. The site has an index to stations in Auckland.

In the UK, The Met Office has developed a service called Weather Observations Website where privateer weather station data is mapped alongside Met Office data as part of a community education, outreach, and data sharing initiative. In Australia, the Bureau of Meteorology will be fostering the same program.