PROSSER, Wash. – Just in time for winter, WSU researchers have launched a Web-based Grapevine Cold Hardiness tool. Based on mathematical simulations of how grapevines respond to cold temperatures throughout the winter, the tool provides estimated low temperature thresholds for bud damage of more than 20 wine and juice grape cultivars.

With AgWeatherNet stations across the entire state, the Grape Cold Hardiness tool enables growers to closely monitor temperatures at their vineyard sites and see, in real time, potential effects on their grapevines. The damage thresholds programmed into the tool represent temperatures that would kill 10, 50 and 90 percent of a particular variety’s primary buds.
If a temperature threshold is reached, a warning statement indicating the estimated level of damage appears on the tool’s Web page. These real-time observations can be found at, the WSU Viticulture and Enology Extension cold hardiness website.
In the fall, grapevines “harden off,” becoming more cold hardy as temperatures decline. The Grapevine Cold Hardiness tool Web page indicates how well a particular cultivar is developing cold hardiness in response to local temperatures.
The tool will be available online starting Dec. 1 at In order to access the tool, you must be a registered user of AgWeatherNet. Registration is free and an online help system is available on the page.
A short how-to video on using the tool can be found on the WSU Viticulture and Enology Extension cold hardiness website at This site also contains valuable information regarding preventing, assessing and responding to cold damage in vineyards.
To prepare Washington growers for dealing with cold damage, WSU’s team of viticulture experts has published a grapevine cold damage management guide, available as a free PDF download at
WSU researchers pioneer in the use of cold hardiness research in the service of vineyard management. Learn the background of the research in an article in a recent issue of WSU’s wine science e-newsletter, “Voice of the Vine:”
Visit WSU AgWeatherNet online to set up personalized weather alerts and much more: