We get around 700 tons from the Texas high plains on a good year for all of our cellar reserve wines and competition wines as well as our small batch wine club wines. We do get juice or grapes from California usually for our simple grocery store (sweet nonvintage) wines but on back years we will...
Well I'm more on the wine side but weather and pricing correlate so both are very good to keep track of. Disease issues, pest problems with the corresponding dates can help with spray schedule. Also harvesting brix levels and dates, that can give you a better understanding on how your grapevines...
Your best bet before planting is to always go to the local wineries and talk with the winemakers. These people will be your primary contacts and partners (because they will be purchasing your grapes).