3.1 Extreme cold temperature.

Grape cultivars differ greatly in their ability to withstand cold winter temperatures and the selection of hardy cultivars for cold sites is important. V.vinifera cultivars are much more sensitive than American cultivars and there are published list of grape winter hardiness (e.g. Clore et al. 1974). Extreme winter minimum temperatures are probably the most important site criteria for New York vineyards. The recommendations of Jordan et al. (1980) are that acceptable sites should have less than two occurrences of -15o F (-26oC) per ten years, whilst good sites stay above this temperature. Shaulis and Detheir (1970) suggest that sites with occurrences of -5oF (-20.5oC) more than once per year are likely to be at risk of cold injury. Martin (1971) suggest -7.6oF (-22oC) as a reasonable cold limit for growing V. vinifera grapes. Tukey and Clore (1972) suggest that there will be little winter injury at -1oF (-18oC) but that -9oF (-23oC) will kill most V. vinifera varieties. Meiering et al. (1980) found that extensive mechanical damage to phloem and xylem layers occurred at -13oF (-25oC). Prescott (1965) quotes French observers who describe 5 to -0.5oF (-15 to -18oC) as 'the ultimate limit of danger in winter'. Winter winds may also serve to reduce the heat budget for a site and thus increase cold injury (Dry and Smart 1988).

The warmest regions in the state are in Long Island and the lower Hudson Valley where temperatures are greater than -13oF (-25oC). The majority of the state has extreme minimum temperatures lower than -25oF (-32oC), however regions such as the Finger Lakes, the Great lakes, the Eastern Plateau have large areas with extreme minimum temperatures between -23 and -25oF (-31 and -32oC) . Within each of these regions there are only small areas where temperatures are slightly warmer, -23 to -18.5oF (-31 to -28oC). The Hudson Valley varies from -25oF (-32oC) in its upper reaches, but is warmer than -14oF (-25.5oC) in parts of the lower reaches. The entire area of Long Island is the warmest part of the State with extreme minimum temperatures warmer than -14oF (-25.5oC). Accordingly, New York State is extremely cold for wine grape production and considerable attention needs to be given to the selection of sites that favor vine survival during periods of extreme cold. All areas of the state must be considered at risk of winter damage. Contrary to published literature values much grape cultivation occurs in regions of the state where temperatures of -20 oF (-29oC) or lower occur. Caution should be given in interpretation of these results since individual sites may be substantially warmer or colder than this because of either local topographic or lake influences. The results of this study differ from earlier work by Mordoff (1949) and the work of Shaulis et al. 1968 whose climatic interpolations show colder temperatures in the Hudson Valley and a stronger influence of the Great and Finger Lakes,  more information has been compiled on this subject.

Figure Lowest winter temperature (oF ) likely to occur in New York State within a 10-year period. Data presented at a 1 km2 resolution.

Methodology for construction of climatic maps

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