Species composition on the islands is closely related to the frequencies of coastal storms that move sea watere and sand across the islands. Low temperatures are not usually a constraint upon plant growth. Growing season can exceed 250 days. The vegetation of the site is very patchy and is composed of areas of high and low salt marshes, unvegetated sand and mud flats, grasslands, shrub savannas and maritime forests. The patterns of vegetation are controlled by variations in the levels of the sea, the land and the fresh groundwater within the land.
Coastal storms are the primary agents of change in the levels of the sea, land and groundwater.
Synoptic Climatology Virginia as a whole is in a zone of westerly movement of air and is on the mean path of winter storms. Southerly and northerly winds are about equally frequent reflecting the progression of weather systems to the east. Northerly winds are more frequent in winter. The state is inundated with tropical moist air in summer and early fall from the South West Atlantic and the Gulf of Mexico. Precipitation is well distributed throughout the year with its source being cyclonic storms in winter and convectional storms in summer.