Downpour after drought in April

Otago may have been declared to be in drought in early April but by the end of the month some towns in the region had received their first significant rainfall in nearly a year.

Most monitoring sites in Otago received normal or above normal rainfall for April after months of low falls, National Institute of Atmospheric Research (Niwa) climate scientist Georgina Griffiths said.

"There has been a turnaround."

The last time Dunedin airport, for example, had experienced more than its normal rainfall was in May last year, when it recorded 166mm (277% of monthly normal) and the highest rainfall between then and March was 53mm (75% of monthly normal) in January, she said.

Last month, it recorded 63mm (139% of monthly normal).

Inland, the situation in Ranfurly, which received 45mm (115% of monthly normal) in April, was similar, Ms Griffiths said.

Its last significant rainfall was in May last year when 65mm was recorded (200% of monthly normal) and the most rainfall it had recorded before April was 41mm (82% of monthly normal) in January.

Raineffects hydrologist Dave Stewart said the rain came mostly in the last week of April and although it would help soil moisture levels, it was "a bit late for significant growth".

However, if May was mild enough, the rain had brought enough moisture to allow some grass growth, he said.

It had also been noted there were fewer frosts than usual in April and those that did occur were milder, Mr Stewart said.

Niwa's April monthly climate report showed Milford Sound and Manapouri recorded their highest April rainfall since their records began, with 1424mm (240% of normal) and 271mm (316% of normal) respectively.

Extreme one-day rainfall highs were also recorded on April 25 at Manapouri, 79mm, and Queenstown, 62mm.

Otago, as did other areas around the country, experienced a warmer than usual April with temperatures in some towns about 1degC above normal, although the region received below average sunshine.

Dunedin airport's average temperature was 1degC above normal at 11.7degC, Musselburgh .8degC warmer at 12.7degC, Queenstown 1.3degC warmer at 11.1degC and Manapouri 2.5degC warmer at 11.9degC.

Cromwell broke its April record with its mean maximum daily temperature 20degC (2.8degC above normal).

Dunedin airport recorded its second highest temperature since records began with 17.7 degC (1.1degC above normal).

Alexandra broke its mean minimum air temperature record with 6degC (2.3degC above normal).

Near record daily minimums were recorded on April 5, -1.8degC at Dunedin airport, its second lowest, and Balclutha -2.3degC, its equal second lowest, while Alexandra recorded its highest minimum of 15.2degC on April 13.

April rainfall in Otago

• Dunedin airport: 63mm; 139% of normal.

• Dunedin, Musselburgh: 50mm, 86% of normal.

• Middlemarch: 46mm, 128% of normal.

• Ranfurly: 45mm, 149% of normal.

• Queenstown: 140mm, 229% of normal.

• Wanaka: 82mm, 168% of normal.

• Oamaru: 55mm, 80% of normal.

• Alexandra: 47mm, 68% of normal.

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