AgWeatherNet is the Washington Agricultural Weather Network and can be used to monitor temperatures, precipitation, pan evaporation, and other parameters at weather stations at over 130 locations in Washington. Conditions in your vineyard may vary depending on the vineyard’s mesoclimate.
Evapotranspiration (ETA) is a measurement of the amount of water lost to the environment via evaporation from the ground surface and from the plant leaves. It can be used to estimate grapevine water use when making irrigation decisions.
ETA is calculated by multiplying the Penman ETo grass (pan evaporation) value for your site by our grapevine crop coefficient (KC) which was derived from fully irrigated Cabernet Sauvignon so it will give an estimate of grape ETA under full irrigation. If you are using deficit irrigation to manage your canopy, you will want to use less than full irrigation replacement. Your final irrigation decision should be based on several factors: grapevine ETA, specific knowledge of your mesoclimate, and your individual goal for your vineyard.