Weather Facts

Summer and Winter Precipitation Amounts - A Comparison of the West and East Coasts of the United States

Believe it or not, the summer is our wettest season here in the Hampton Roads area. While in California, the winter is the rainiest season. You might find it hard to believe that we receive more precipitation here in the summer than the winter but here is why. Rainfall during the summer is primarily from thunderstorms and they can produce a lot of rain in a short period of time. Also, tropical cyclones and their remnants add to our rainfall totals during the summer months. We all know how heavy rainfall can be from those systems. During the winter months, you may have quite a few rainy days, but the rain is usually of a light to moderate intensity. In California, thunderstorms are quite rare during the summer and tropical cyclones do not impact them, so they donít get a lot of summer rainfall. This is caused by several factors but primarily the water temperature of the Pacific is what keeps California dry during the summer months. The water is so cool that it doesnít give off much moisture. This cool water also helps to stabilize the atmosphere. The summer weather patterns also donít bring many storm systems to the west coast. During the winter, the storm track across the Pacific drops southward and occasionally storms batter the west coast. Here on the east coast, the water is much warmer due to the Gulf Stream. This warm water adds moisture in the form of our summer humidity which we all know can be quite oppressive. Weather patterns bring additional moisture up from the Gulf of Mexico which add even more to our rainfall totals. Note that in the Pacific Northwest, rainfall is a bit higher than it is in California in the summer due to an occasional low pressure storm system making it far enough south to bring some rain that part of the country. The storm track during the summer normally doesn't bring storms into that area. However, winter is by far the wettest season up there, too.