3 JULY

THE NEW ZEALAND GAZETTE

CLIMATOLOGICAL TABLE—Summary of the Records of Temperature, Rainfall, and Sunshine for May 1975—continued

The “normal” refers to the present site of the instruments. Standard periods for normals are: Temperature 1931–60, Rainfall 1941–70, Sunshine 1941–70. No normals are available for stations with only short records.

*Indicates that the sunshine recorder is not located at the station but is in the near vicinity.

A rain day is a day with rainfall equal to or greater than 0.1 mm.

Where the extremes of temperature and rainfall have occurred more than once during the month, the date of the first occurrence is given.

NOTES ON THE WEATHER FOR MAY 1975

General—May was a warm month and, like April, it was marked by more frequent winds from a westerly quarter than usual. The westerlies were particularly persistent during the third week, which was also the warmest part of the month. Rain was especially welcome in the North Island, which had been rather too dry in April. Most farmers found May a favourable month but in some districts the ground became too wet.

Rainfall—Rainfall was above normal over most of the North Island. It was more than double the normal value in the Hauraki Plains and parts of Coromandel, and also in an area extending northeast and southwest from Whangarei Aerodrome. By contrast, it was less than a quarter of the normal value in the Bay of Islands-Kaitaia area. In the South Island rainfall was above normal west of a line from Lake Rotoiti in Nelson extending southwestward to Alexandra and then southward through Gore. To the northeast and east of this line, rainfall was below normal. It was less than half on the Canterbury Plains and Banks Peninsula, and also in parts of Marlborough and Nelson. A small depression which was nearly stationary over northern Northland on the 30th caused exceptionally heavy rain in some areas near Whangarei, with flooding and slips. The Aerodrome reported 309 mm for the day’s total, and nearly all of this fell in 12–15 hours.

Temperatures—Temperatures were above normal. North of Hokitika and Ashburton the departures were 1–2°C, but south of this temperatures were only slightly above normal.

Sunshine—Sunshine was below normal over nearly all of the North Island and also on the west coast of the South Island north of Haast. The deficiency was mainly 20–30 hours but was up to 40–50 hours in the King Country, where Taumarunui received a record low May total of 67 hours. East of the ranges in the South Island sunshine was above normal, mainly by 25–55 hours.

Weather Sequence—At the beginning of May an anticyclone was centred east of the South Island, while a complex depression covered the South Tasman Sea, and another depression was centred to the northeast of Auckland. Rain was reported on the West Coast and also in eastern Northland and the Gisborne ranges, and scattered light falls affected other parts of the South Island. The depression over the South Tasman Sea crossed the South Island during the 2nd and 3rd with an associated trough of low pressure. Rain became fairly general but the weather soon cleared in Fiordland. On the following day temperatures became cooler as the winds turned to southwesterly, and some rain was still reported over most of the North Island.

On the 5th a trough in the southwesterlies brought rain to the Southland coast. During the two following days temperatures became much colder as the winds changed to southerlies, and showers affected many districts. On the 8th an anticyclone covered the country, with mainly fine weather. However, a depression to

the north caused some rain in eastern Northland and on the Bay of Plenty coast. Temperatures were once again comparatively warm.

On the 10th a depression to the north moved slowly southeastward past Auckland to East Cape, and rain was reported in an area extending from Hamilton and Tauranga eastward and southward to East Cape and Napier. At the same time a trough of low pressure brought rain to the West Coast and also Otago and Southland. On the following day the depression moved to the east of the North Island and most places reported some rain. On the 12th a weak trough of low pressure was approaching the South Island, but the weather was mainly fair.

The 10 days from the 13th to the 22nd were marked by pronounced westerly conditions. Pressures remained high to the north and very low to the south and southwest. A particularly deep depression passed far to the south on the night of 22–23. The whole period was warm, especially in the east, except on the last day in the South Island. Rain was persistent and often heavy on the West Coast, and over most of the period it also affected the North Island west of the ranges. Some lighter falls extended east of the ranges at times in both Islands on the 18th and 22nd. Strong winds from the north and northwest buffeted many areas, especially about Cook Strait.

On the 23rd and 24th a depression was centred east of the North Island and westerly to southwesterly winds covered the whole country, with rather cold temperatures in the south. Rain affected the West Coast, Southland and Otago, and also districts west of the ranges in the North Island from Manawatu to Waikato and Bay of Plenty. On the following day a trough became stationary over the North Island while pressures rose to the south, causing a change to southerly winds in some areas. Rain persisted in the same areas of the North Island and also affected the northern half of the South Island. On the 26th a small depression crossed Cook Strait while pressures were high to the southwest. Rain spread over the remainder of the North Island. Temperatures remained colder than normal in the south but warmer than normal in the north. During the 27th and 28th an anticyclone extended over the South Island from the Tasman Sea while a second depression crossed the North Island. The rain cleared over most of the South Island. Temperatures were very cold south of Auckland. During the next two days this depression was almost stationary over Northland. Rain still affected most of the North Island, and some exceptionally heavy falls were recorded around and north of Whangarei, causing flooding and slips. By the last day of the month the depression was centred east of Northland. The rain spread to some northern areas of the South Island. Considerable falls were reported in the eastern half of the North Island.

J. F. de LISLE, Director.

(N.Z. Met. S. Pub. 107)