Both Pinot Noir and Chardonnay require about 1150 heat degree days to ripen; it is how those units are accumulated that is important and we believe long and slow is best. Most commentators agree that marginality is key to quality (both will obviously ripen quickly in a hot climate but the result will be of very poor quality).
According to the Bureau of Meteorology, southern Victoria has a climate which experiences "warm summers and cold winters" and "wet winters and low summer rainfall". Located around latitude 38, and with the sea on three sides, the Mornington Peninsula modifies this and has a cool maritime climate with a long, slow ripening season that encourages the development of the complex and elegant flavours of this region’s finest wines.
Also see vintages for more detail on climate.
Being on a peninsula we enjoy the moderating influence of water, suffering neither the extremes of spring and autumn frosts that can attack other cool climate regions, nor the excessive heat continentality can bring. While some higher latitude regions achieve ripeness from higher average temperatures associated with long summer daylight hours but a shorter growing season, our ripeness evolves more slowly from earlier budburst and longer, more stable autumns which produce complex elegant flavours, high natural acidity and fine tannins.
The perceived wisdom is that high diurnal temperature ranges are necessary - exposure to sunlight increases ripening while the drop in temperature at night preserves the acids in the grape. John Gladstones believes this is incorrect, that cold nights retard physiological ripening and quality development. He believes that a narrow range of variation is preferable, pointing out that "the best wine-producing regions of Europe are all characterised by narrow ranges of day-night and day-to-day temperature variation through the growing and ripening seasons, as are, even more, the best vineyard sites within them." Gladstones calculates a temperature variability index (the lower the number, the less the variability) which gives the following (unadjusted) results for selected sites...
Far too involved to go into here but fascinating in the context of the maritime influence which obviously has the effect of reducing variability, well worth reading the original.
The Peninsula as a whole benefits from the cooling influence of sea breezes from Port Phillip and Westernport Bays but in the southern portion, Main Ridge, we experience the additional, very cool ocean breezes directly off Bass Strait. These find their way up the valleys which lead from the coast up to the spine of Main Ridge and intensify the difference between Main Ridge and the warmer, lower, northern Peninsula.
In addition, in the evening, cool katabatic winds flow down from the ridge, through the valleys, creating a further cooling influence, particularly on the lower Wallis Vineyard.
Main Ridge forms the higher, southern part of the Peninsula; its highest point, Arthurs Seat, is at 305m and our vineyards range from 206-142m – altitude reduces temperature by 0.6°C/100m so Main Ridge is naturally cooler (0.6°C may not seem much but in terms of heat degree days taken over a growing season it becomes meaningful). From the roughly east-west running spine of Main Ridge, the ridges and valleys flow from north to south down to Bass Strait producing diverse pockets of terroir. This provides the varying topography for our unique vineyard sites.
|(north of region)||(south of region)||(east of region)|
Heat Degree Days (Oct-Apr)
(cut off at 19ºC but
otherwise not adjusted)
(raw data not adjusted)
|Sunshine Hours (Oct-Apr)||
|Annual Rainfall (mm)||737||751||719|
|Rainfall (mm) (Oct-Apr)||385||376||365|
|Mean January Temperature||19.2°C||17.6°C||19.1°C|
|Relative Humidity (3pm, Oct-Apr)||55%||73%|
|(Source: Bureau of Meteorology)|