Met Report Table 1: Blenheim Weather Data – August 2011 August 2011
August 2011 compared to LTA
August LTA
Period of LTA
August 2010
GDD’s for month -Max/Min¹ GDD’s for month – Mean²
18.1 38.9
109% 114%
16.6 16.6
(1996-2010) (1996-2010)
25.0 37.5
Growing Degree Days Total Jul – Aug 11 – Max/Min Jul - Aug 11 – Mean
23.2 57.0
87% 101%
26.6 56.7
(1996-2010) (1996-2010)
26.8 52.7
Mean Maximum (°C) Mean Minimum (°C) Mean Temp (°C) Mean Temp (°C)
14.6 2.2 8.4 8.4
+1.1°C -0.8°C equal -0.5°C
13.5 3.0 8.4³ 8.9³
(1932-1980) (1932-1980) (1932-200) (1986-2009)
14.6 5.5 10.1 10.1
Grass Frosts (<= -1.0°C) 17
1.6 more 6.2 more
15.4 10.8
(1932-1980) (1986-2009)
5
Air Frosts (0.0°C) 8
0.4 more 4.0 more
7.6 4.0
(1932-1980) (1986-2009)
1
Sunshine hours 235.0 133% 177 Sunshine hours – lowest 129.2 Sunshine hours – highest Sunshine hours total – 2011 1536.8 99% 1545.0
(1935-2000) 1941 2011 (1930-2000)
155.8
Rainfall (mm) 52.6 82% Rainfall (mm) – lowest Rainfall (mm) – highest Rainfall total (mm) -2011 425.0 95%
64 4.6 172.1 446.0
(1930-2000) 1969 1990 (1930-2000)
1471.4 83.2 549.8
Evapotranspiration – mm
68.6
144%
47.6
(1996-2010)
47.3
Windrun (km)
218.1
89%
245.7
(1996-2010)
207.1
Mean soil temp – 10cm
5.2
-1.2°C
6.4
(1986-2010)
9.0
Mean soil temp – 30cm
7.2
-1.2°C
8.4
(1986-2010)
9.8
¹GDD’s Max/Min are calculated from absolute daily maximum and minimum temperatures ²GDD’s Mean are calculated from average hourly temperatures ³Mean temperature for two long-term average periods provided as a contrast Sunshine Hours August 2011 has entered the record books as the sunniest August on record for Blenheim for the 82 years 1930-2011. August recorded 235 hours sunshine, beating the previous highest total of 225.8 hours recorded in 1972. The only down-side re the sunshine was that Nelson managed to record 12 hours more than Blenheim for August. Nelson is now 44 hours ahead of Blenheim so far in 2011. However, with the high August total, Blenheim has leapfrogged ahead of Whakatane, into second place behind Nelson. Possible Sunshine Most readers will probably be unaware of how the sunshine that Blenheim receives actually relates to the possible sunshine. “Possible sunshine” is the number of hours during the day when sunshine could be recorded, i.e. assuming no clouds in the sky to block the sun. The actual number of hours of
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09/2011 WINEPRESS
sunshine received can be expressed as a percentage of the possible hours. The long-term annual average sunshine for Blenheim (1930-2010), is 2457 hours. The possible sunshine hours are 4256, i.e. on an annual basis Blenheim receives only 58 percent of possible sunshine hours. However, 235 hours sunshine for August 2011 was 75% of possible. Given that Blenheim is one of the sunniest locations in New Zealand, the figure of only 58 percent of possible sunshine received, indicates how New Zealand is aptly named the ‘Land of the long white cloud’. Being long narrow islands surrounded by ocean, New Zealand experiences a lot of cloud-cover. Other NZ locations and percentage of possible sunshine received are as follows: Auckland 50%, Palmerston North 42%, Wellington 48%, Nelson 57%, Christchurch 47%, Gore 39%, Greymouth 40%. Someone needs to remind Nelson that they are not supposed to receive as much sunshine as Blenheim.
The Official Magazine of Wine Marlborough
In contrast, the sunniest city in the world is Yuma, Arizona, USA, which receives approximately 4100 hours sunshine per annum, or 90% of 4555 possible hours. Temperature The Met Report one year ago detailed that 2010 recorded the fourth warmest (10.1°C) and 2009 the warmest (10.9°C) August on record for Blenheim, for the 79 years 1932-2010. Three of the warmest August mean temperatures on record for Blenheim occurred in the six years between 2005 and 2010. The mean temperature for August 2011 of 8.4°C is in complete contrast to those in 2009 and 2010. Table 2 indicates the markedly differing weekly temperatures during August 2011 and how they compare with August 2010. The second week of the month was 2°C below the long-term August average of 8.4°C, whereas the fourth week of the month was 3.8°C above the long-term average. In fact the average temperature of 12.2°C in the final week of August was also well above the September average (10.6°C), and not too far below the October average (12.7°C). Table 2: August 2011 and 2010 weekly mean temperatures Week 2011 2010 1-8 8.0 10.7 9-16 6.4 9.7 17-24 7.5 9.7 25-31 12.2 10.2 Mean 8.4 10.1 L.T.A 8.4 It is interesting to note that the average daily maximums for August 2011 and 2010 were both 14.6°C. However, the average daily minimum was 2.2°C in 2011 and 5.5°C in 2010. The average daily range in temperature of 12.4°C in August 2011, is the highest on record for the 26 year period 1986-2011. Chill Hours In all the Met Report articles that I have written I don’t think that I have ever summarised chill hours. This is mainly because grapes do not require a large amount of winter chilling and chill hours are not normally reported for viticulture. Some New Zealand horticultural magazines report winter chilling, especially with reference to the production of stone fruit, such as
