Further to my recent post I updated some of my maps following some discussions I’ve had. I’ve added some climate indices, namely Growing Degree Days and the Huglin Heliothermic Index. I could add in other standard ones too but have decided not to since it’s my view that since these indices are measures calibrated on less marginal viticultural climates, and their use in a marginal climate should be done with caution. Unsurprisingly the resultant mapped indices are highly correlated with the temperature map. The slight exception is that the Huglin Index map shows more high-value areas inland than the GDD or temperature maps do. This is explained by a slight continentality effect because it uses the average of maximum temperature and mean temperature as its driver, rather than just mean temperature.
All metrics Apr-Oct (incl), except frost (Apr&May) and Huglin (Apr-Sept); averages from 2001-06 inclusive, monthly data; darker colour means metric is greater than light colours.