Weather Data summary for April 2016 for the Blenheim Meteorological station located at Grovetown Park
Campus of the Marlborough Research Centre.
April 2015 was very sunny, dry and warm
Sunshine
238.3 hours sunshine for April was 127% of the long-term average for April of 187 hours (1930-2015)
April 2015 recorded 162.5 hours sunshine.
April 2014 recorded 123.7 hours sunshine.
April 2015 is now the second sunniest April on record for Blenheim for the period 1930-2016. Second only to 1958
which recorded 238.5 hours sunshine.
Total sunshine from January to April 2016 is 1001.9 hours. This is second sunniest first four months of the year for
Blenheim. Sunniest January to April is 1994 with 1008.6 hours sunshine.
The sunniest town in New Zealand in April 2016 was Nelson with 248 hours sunshine followed by Blenheim with
238.3 hours. Whakatane recorded 200.1 hours in April, 38.2 hours less than Blenheim. After the first four months of
2016 the rankings are as follow:
Blenheim
1001.9 hours
Nelson
984 hours (17.9 hours behind Blenheim)
Tekapo
922.6 hours (79.3 hours behind Blenheim)
Whakatane 875.1 hours (126.8 hours behind Blenheim)
Rainfall
25.6 mm of rain in April was 48% of the long-term average for April of 53.2 mm (1930-2015)
April 2015 rainfall was 52.0 mm.
April 2014 rainfall was 149.8 mm. 4th highest rainfall total for April
April 2013 rainfall was 102.5 mm.
April 2016 recorded rain on four days during the month. However, 1 April recorded 23.6 mm, or 92% of the month’s
rainfall. The other three days only recorded a total of 2.0 mm. This was a similar pattern to March 2016, which
recorded 46.8 mm rain, of which 45.0 mm fell on the 23rd.
As virtually all April’s rainfall fell on the 1st of the month it meant that April was very dry from 2nd to 30th.
Soil moisture (5-35 cm depth)
Shallow soil moisture started the month on 28% and rose to 34.2% on 2nd, after 23.6mm rain. However, from
2nd to 30th, soil moisture dropped by 10.5%, to be 23.7% on 30th April.
Seasonal water deficits for Blenheim (September to April - 1996-2015)
As explained on previous occasions the seasonal water deficit is the difference between rainfall and
evapotranspiration. It is the amount of water that would need to be supplied from irrigation to keep a grass pasture
actively growing throughout the season.
1997-98
2000-01
2014-15
2015-16
Long-term average
Water Deficit (mm)
-701.9
-700.0
-642.3
-698.5
-483.7
Rainfall (mm)
242.5
176.6
220.8
240.2
366.6
Evapotranspiration (mm)
944.4
876.6
863.1
938.7
850.3
It is interesting to note that the seasonal water deficit for the 2015-16 season (-698.5 mm) was 214.8 mm greater than
the long-term average. It was also 56.2 mm higher than the 2014-15 season (-642.3 mm).
The 2015-16 season is the second season in a row with extremely high water deficit. Both seasons recorded very low
rainfall. However, evapotranspiration in the 2015-16 season was well above the 2014-15 season and also well above
average.
For the second year in a row there would have been a much greater need for irrigation than in an average year.
Temperature
Mean temperature of 13.9°C was 0.5°C above the long-term average temperature for April of 13.4°C (1986-2015).
April 2015 mean temperature was 14.2°C.
April 2014 mean temperature was 14.5°C.
April 2013 mean temperature was 14.7°C.
Weekly temperatures in Blenheim during April 2016
Mean Maximum Mean Minimum
20.6
9.1
1 – 7 April
20.0
10.4
8 – 14 April
19.0
5.6
15 – 21 April
19.3
8.0
22 – 28 April
4.5
29 – 30 April (2 days) 18.9
April 2016 Average
Long-term average
1986-2015
19.7
18.8°C
+0.9°C
8.0
8.0°C
Equal
Mean
14.9
15.2
12.3
13.7
11.9
13.9
Deviation
+1.5°C
+1.8°C
-1.1°C
+0.3°C
-1.5°C
+0.5°C
13.4°C
The first two weeks of April 2016 were very warm, with both warm day-time and night-time temperatures. With the
arrival of the third week of the month the overnight minimum temperatures plummeted while the daily maximum
temperatures stayed above average.
Although April 2016 recorded a cooler mean temperature than in 2013-2015, you need to bear in mind that all four
years were well above the long-term average for April.
Coldest and Hottest days during April
One ground frost was recorded during April.
The coldest minimum temperatures were recorded on the morning of 21 April, with an air minimum of 2.9°C and a
grass minimum (ground frost) of -1.5°C.
The hottest day was 3 April with a maximum temperature of 25.7°C.
Wind Run
April 2016 recorded average daily wind run of 211.3 km compared to the long-term average of 223.3 km.