THE RUTHERGLEN CLIMATE
We are often told that in winemaking terms Rutherglen is a “hot” climate. This is why it makes such wonderful fortified wines. It is also claimed that this is the reason it shouldn’t make table wines.
There is no denying that Rutherglen is a warm and sunny spot - but so are many other well known Australian table wine regions. A brief examination of climatic data best illustrates the fallacy that Rutherglen is too hot for table wine production.
The attached table shows a range of different climate measures. Of these the Heat Degree
Days System (HDD) is probably the most widely used and understood system available. It has its flaws but nor can it be completely ignored. It shows Rutherglen with a HDD of
1770 `C - exactly the same as Clare and well below the figures for Cowra, Mudgee, Hunter
Valley and McLaren Vale. No one is suggesting that any of these regions cannot make table wines. Whenever wine buffs start discussing fine Riesling one of the first places mentioned is Clare. By any measure Cowra is a very hot climate. This doesn’t stop anyone enjoying Cowra Chardonnay. Grapes need warmth and sunshine to ripen. It is how that fruit is handled and turned into wine that can make the critical difference.
Rutherglen is a very continental climate ie there is a big range of temperature variation between the warmest and coldest months as well as in the daily temperature range. This is shown by the Marginality figure (Mar) on the attached sheet. This means that throughout vintage, Rutherglen (like other highly continental climates such as Cowra and Mudgee) experiences warm, sunny days and very cool clear nights. This is one of the key factors in slowing the ripening processes of the fruit and providing such high quality fruit.
The other key figure for Rutherglen is that of sunshine hours (SSH). This is higher than for any of the other areas - not hotter, just more hours of sunshine. We believe this plays a significant part in producing the lusciously ripe fruit that make Rutherglen fortifieds so outstanding. It is not a sudden burst of heat but slow and even ripening. The result is that fruit remains in good condition and with a good sugar/acid balance.
Other warm winemaking regions can undoubtedly produce good fortifieds. All they will have to do is to build up stocks over 120 years or so as Rutherglen has. Maybe then they will have some of the depth and complexity that sets Rutherglen fortifieds in a class of their own.
The fallacy is not that Rutherglen is a warm climate, the fallacy is th at “Rutherglen can’t make table wines”. The climate produces high quality winemaking grapes. Through use of sound, modern winemaking techniques producers such as Campbells are able to turn this fruit into table wines of great quality. The only way to judge this is to taste the wine and assess it on its merits. Don’t let your views be coloured by widely reported misconceptions such as “Rutherglen is too hot to make table wine”.
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CLIMATIC FIGURES
Wine Region MJT ( 0 C) Mar ( 0 C) HDD ( 0 C) Annual
Rain
(mm)
Cowra
Mudgee
Cessnock
(Hunter Valley)
Rutherglen
Clare
23.5
22.9
22.7
22.3
21.9
McLaren Vale 21.7
Nuriootpa 21.4
(Barossa)
Margaret River 20.4
15.5
15.0
12.8
15.4
13.6
10.8
12.6
2070
2050
2070
1770
1770
1910
1710
660
670
740
590
630
660
500
Oct-Apr
Rain
(mm)
370
360
530
260
200
180
160
Aridity
(mm)
330
300
(50)
380
430
420
460
RH
%
51
SSH
(hours per day)
9.0
63 8.0
58 7.3
50
47
49
47
9.3
8.8
8.6
8.8
7.6 1690 1160 200 400 62 8.1
EXPLANATION OF CLIMATIC FIGURES
MJT Mean January Temperature
Mar Marginality - difference between Mean January and Mean July
temperature.
HDD Heat Degree Days = difference between mean temperature of month and
10’C multiplied by number of days in month, then adding figures for the seven growing months (Oct to April) together.
Aridity
RH
The difference between rainfall and 50% evaporation.
Relative Humidity (calculated as mean for January at 9am).
SSH Sunshine Hours - mean sunshine hours per day in the growing season.
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