Press Release July 2017

Weather Data summary for July 2017 for the Blenheim Meteorological station located at the Grovetown Park campus of the Marlborough Research Centre.

 July 2017 recorded very close to average air temperature, rainfall, sunshine and number of frosts

 Rainfall

Total rainfall of 62.4 mm was 99% of the long term average for July of 63.0 mm (1930-2016).

Blenheim escaped the high rainfall recorded in some other parts of New Zealand during July

All four years 2013 to 2016 recorded well below average rainfall during July

July 2016 rainfall was 34.8 mm.

July 2015 rainfall was 35.2 mm.

July 2014 rainfall was 10.0 mm; lowest July total on record

July 2013 rainfall was 34.8 mm

13 days during July 2017 recorded rainfall. However, of the 62.4 mm rain, two days accounted for 78% of the rain. 15.6 mm (25%) on 1 July, and 33.0 mm (53%) on 20 July.

Total rainfall for January to July 2017 of 405.4 mm is 108% of the long-term average of 374.6 mm.

Temperature

The mean temperature of 8.0°C was 0.1°C above the long-term average temperature for the past 31 years (1986-2016) of 7.9°C.

July 2016 mean temperature was 8.7°C.

July 2015 mean temperature was 7.5°C.

July 2014 mean temperature was 7.5°C.

Table 1: July 2017 temperatures and frosts for Blenheim

Mean Max Mean Min Mean   Deviation Total Ground Frosts Total Air Frosts
1-7 July 12.3 3.4 7.8             -0.2 2 2
8-14 July 12.7 3.0 7.8             -0.2 3 0
15-21 July 14.0 2.4 8.2             +0.2 3 2
22-28 July 14.4 4.4 9.4             +1.4 2 0
29-31 July 12.2 -1.9 5.2             -2.8 3 3
           
1-31 July 13.2 2.8 8.0             +0.1 13 7
Long-term average

1986-2016

13.1 2.6 7.9 15.1 7.4

 The average daily maximum temperature of 13.2°C was 0.1°C above average

The average daily minimum temperature of 2.8°C was 0.2°C above average

 Frosts

July 2017 recorded 13 ground frosts and 7 air frosts

July 2016 recorded 12 ground frosts and 2 air frosts

July 2015 recorded 19 ground frosts and 11 air frosts

July 2014 recorded 17 ground frosts and 10 air frosts

Long-term average ground frost number for July is 15.1 over the past 31 years (1986-2016).

Long-term average air frost number for July is 7.4 over the past 31 years (1986-2016).

Frost numbers in July 2017 were close to the long-term average over the past 31 years

Monday 31 July recorded the coldest ground frost of -6.8°C. (-4.6°C on 1 July 2016)

Monday 31 July recorded the coldest air frost of -2.0°C.  (-0.7°C on 2 July 2016)

The last three days of July 2017 were the coldest days of the month, with very similar minimum air and ground temperatures on each of the three days. These last three days of July 2017 all recorded minimum temperatures well below the coldest temperature in July 2016.

In Blenheim, the coolest part of the day is generally between midnight and 9am.  Over the last three days of July there were quite long periods when the temperature remained below zero.

29 July – below zero for 8 hours from 1 am to 9 am. Mean temp for 8 hours of -1.35°C. Absolute min = -1.9°C

30 July – below zero for 10 hours from 10 pm to 8 am. Mean temp for 10 hours of -0.78°C. Absolute min = -1.7°C

31 July – below zero for 7 hours from 1 am to 8 am. Mean temp for 7 hours of -1.25°C. Absolute min = -2.0°C

 Sunshine

157.0 hours sunshine for July 2017 is 98% of the long term average for July of 159.8 hours (87 years 1930-2016).

All four years 2013 to 2016 recorded well above average sunshine hours in July.

July 2016 recorded 190.9 hours sunshine

July 2015 recorded 199.1 hours sunshine (third highest total on record)

July 2014 recorded 173.6 hours sunshine.

July 2013 recorded 181.4 hours sunshine.

July 2012 recorded 131.1 hours sunshine.

Total sunshine hours for Blenheim for January to July 2017 are 1423.3; or 103% of the long-term average total of 1377.2 hours.  The total for January to July 2016 was 1514 hours;

 Sunshine hours (from NIWA) up until 30 July, put Blenheim in third place in the race to be the sunniest town in New Zealand for 2017. Whakatane is out in front, 38 hours ahead of Blenheim, and Richmond is in second place only 7 hours ahead of Blenheim.

Rob Agnew

Plant & Food Research / Marlborough Research Centre

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Filed under Blenheim Weather Data, Weather Press Releases.

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