is one of Australia's hottest and wettest wine regions. Flanked by mountains to the west and north the Hunter Valley acts as a funnel, pulling cool ocean breezes into the area. This effect is similar to the cooling that Napa Valley receives from San Pablo Bay in California. Without these cooling breezes, quality wine grape production would be nearly impossible. However, with those cooling breezes also comes heavy rainfall and periodic cyclonic storms in the summer and autumn months. In the summer, the average daily temperature regularly exceeds while during the winter the temperature averages around . Through the growing year, January tends to be the warmest month while July is usually the coolest. Temperatures during the peak growing month of January average between , with the temperature becoming progressively hotter the further inland you move away from the cooling influence of the sea. During the growing season the Hunter Valley receives an average of 7.3–7.5 hours of sunshine a day, but with the cloud cover coming in off the ocean the sunlight is slightly diffuse which gives the vines some protection from heat stress. During the growing season the Lower Hunter will average around 2070 degree days (Celsius) with the Upper Hunter having 2170 degree days putting it under the Winkler heat summation scale as a Region IV. Mid-latitude westerly winds bring high pressure weather front that alternate with cold fronts on the winter. This leads to generally drier conditions in the winter months of July and August. In the summer, southeasterly winds bring weather fronts harbouring extensive amounts of moisture. Between October and April more than two thirds of the region's annual rainfall will fall with January and February being the wettest months. As much as of rain can fall during harvest months, creating the Hunter's biggest viticultural hazard, though the inverse problem of winter drought can also be a problem. The rain, coupled with the heat, encourages high relative humidity in the region and subsequent threat of mould. During the growing season months of October–April, the 3pm average for relative humidity in the Lower Hunter is 49%, while it is 43% in the Upper Hunter. Wine regions and subregions The Hunter Valley Wine Zone Australian Geographical Indication was registered on 1 May 1996 and is approximately the entire Hunter River catchment. It contains only one named wine region, Hunter. The Hunter Wine Region Australian Geographical Indication was