Press Release May 2018

Weather Data summary for May 2018 for the Blenheim Meteorological station located at the Grovetown Park campus of the Marlborough Research Centre.

May 2018 recorded well above rainfall, slightly above average mean temperature and wind-run and average sunshine hours

Table 1: Weekly temperatures, rainfall and sunshine during May 2018
Mean Max
(°C) Mean Min
(°C) Mean
(°C) Rainfall
(mm) Sunshine
(hours)
1st – 7th 17.0 (+0.5) 7.3 (+1.5) 12.2 (+1.1) 7.2 41.6
8th – 14th 18.0 (+1.5) 9.7 (+3.9) 13.9 (+2.8) 27.2 25.5
15th – 21st 16.7 (=) 8.6 (+2.8) 12.7 (+1.6) 42.6 39.2
22nd – 28th 14.0 (-2.5) 2.9 (-2.9) 8.5 (-2.6) 8.2 41.9
29th – 31st (3 days) 12.2 (-4.3) 0.3 (-5.5) 6.3 (-4.8) 0.0 23.0

1 – 31 May 16.0 (-0.5°C ) 6.5 (+0.7°C) 11.3 (+0.2°C) 85.2 (149%) 171.2 (98%)
LTA 1986-2017 16.5 5.8 11.1 57.2 175.2

Sunshine
171.2 hours sunshine for May was 98% of the long-term average for May of 175.2 hours (1986-2017).

May 2017 recorded 205.4 hours sunshine
May 2016 recorded 167.8 hours sunshine
May 2015 recorded 214.5 hours sunshine (sunniest May on record 1930-2018)

Blenheim has recorded 1067.5 hours sunshine for the five months January to May 2018; 98% of the long-term average of 1085.4 hours.

Sunshine totals for January to May 2018
Richmond 1069.0 hours
Blenheim 1067.5 hours (1.5 hours behind Richmond)
Napier 1042.4 hours
Waipara 1031.1 hours
Tekapo 1022.7 hours

Still a very close race between Richmond and Blenheim

Rainfall
Rainfall total of 85.2 mm was 149% of the long term average for May of 57.2 mm (1986-2017)
May 2017 rainfall was 57.2 mm.
May 2016 rainfall was 89.2 mm.
May 2015 rainfall was 20.0 mm.

Total rainfall for the first five months of the year over the past four years makes for an interesting comparison.

Total rainfall for the five months January to May 2018 was 452.8 mm; 191% of the long-term average of 236.8 mm.
Total rainfall for the five months January to May 2017 was 324.6 mm; 129% of the long-term average.
Total rainfall for the five months January to May 2016 was 248.8 mm; 99% of the long-term average.
Total rainfall for the five months January to May 2015 was 129.0 mm; 51% of the long-term average.

i.e. Blenheim has recorded 3.5 times the rainfall from January to May 2018, compared with 2015

Soil Moisture
Average soil moisture for May 2018 was 37.6 %, compared to the long-term average of 31.8%.

Temperature
Mean temperature of 11.3°C was 0.2°C above the long-term average temperature for May of 11.1°C (1986-2017).
May 2017 mean temperature was 10.4°C
May 2016 mean temperature was 12.6°C

Frosts
May 2018 – 5 ground frosts and 2 air frosts.
May 2017 – 5 ground frosts and 1 air frost.
May 2016 – 2 ground frosts and 0 air frosts
May 2015 – 8 ground frosts and 3 air frosts

The coldest morning during May 2018 was the 29th, with an air minimum of -0.4°C and a grass minimum (ground frost) of -3.5°C. These minimum temperatures were warmer than in May 2017.
The coldest morning during May 2017 was the 21st, with an air minimum of -1.5°C and a grass minimum (ground frost) of -5.0°C.

Wind Run
May 2018 recorded an average of 230.7 km of daily wind run. This was above the long-term average of 217 km (1996-2017).
However, the variation in wind-run during May was high. The windiest day was 7 May with 503 km wind-run. The least windy day was 14 May with only 98 km wind-run.

May 2018 is the first month since January 2017 to have recorded well above the average monthly wind-run.

Rob Agnew
Plant & Food Research /Marlborough Research Centre

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Filed under Blenheim Weather Data, Weather Press Releases.

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