To understand the summer winds in Hatteras you need to understand the Bermuda High. This is what causes the wind summer winds in OBX.
The Bermuda High is a high pressure area that is usually centered in the vicinity of Bermuda during the spring and summer. This high pressure area is responsible for the prolonged heat waves in the Eastern part of the country. Since winds blow clockwise around high pressure areas in the northern hemisphere, a south to south-westerly wind transports heat and humidity into the Mid-Atlantic States. During the late spring and summer, cold fronts from the north and west have trouble making inroads into the Hampton Roads area due to the persistent Bermuda Highís influence. The high migrates east and west which causes fluctuations in our weather. There are times when it builds westward and is configured in such a way to change our winds to a south-southeasterly direction. This sometimes brings in a tropical air mass and lots of moisture. The interaction of the warm moist air moving over the land causes shower and thunderstorms that can dump copious amounts of rain. Two factors cause the air to rise. The friction of the land and the heat from the land causes the air to rise high into the atmosphere, This causes condensation which then leads to showers and thunderstorms. The position of the Bermuda High also is a player in steering tropical cyclones towards the west and then northwest. If the high is further out in the Atlantic, the odds are that the cyclones will curve and go out to sea. If the high is further west, there is a good chance that the cyclones can impact the East or Gulf Coasts of the United States
When this is set up strong it can blow Southwest for weeks. We always say it does not matter the forecast as long as the direction is SW. In late May - early August if the forecast is for SW (not S or SE or WSW but SW) then it will blow. As the high builds during the day normally the wind starts off low teens in the AM. By 3:OO it goes to 10M weather and then at 5:30 it can really ramp up to 8m or smaller all the way to dark. Normally it will keep blowing after dark and then slowly die down. The closer it is to being centered over Bermuda the better. Some years the Jet stream is to high or to low and it just does not set up well. Last year was great and there was probably 90% of June and Junly where it blew. If the summer is hot and humid it is usually good, drought summers are usually bad. Since this is a thermal and not a frontal wind pattern, it can make OBX stand out from locations close by. It can be blowing at 25+ in Rodanthe and 10 in Virginia beach only about 90 straight line miles away.