Farming is more often limited by water than cold. Take a look at satellite photos of irrigation (https://www.google.com/search?q=irrigation+circles+google+eart

Farming is more often limited by water than cold. Take a look at satellite photos of irrigation (https://www.google.com/search?q=irrigation+circles+google+earth https://www.google.com/search?q=irrigation+circles+google+ea...) and consider that one of the most serious issues in the western parts of the US is water rights between the states. This will (likely) be getting worse as temperatures increase and evaporation increases. The higher temperatures will also be melting mountain snowpack earlier, so the highly variable rivers that feed much of our irrigation will be getting dry by late June rather than the first week of August with serious impact to crops.