Climatology
Kiawah clearly has a mild climate. The mean
annual temperature is 66 ˚F with an average high in
July of 81 ˚F and a low in February of 49 ˚F. Nighttime
low temperatures fall below 32 ˚F no more than 19
times during a typical year, and daytime highs exceed
91 ˚F about 30 days a year, primarily in July. Winter
winds generally blow from the northwest, whereas from
March to August winds are primarily from the south. In
September to December winds shift gradually from out of
the northeast to blow from the west. Finally, as we know,
the greatest threat to the Island is hurricanes. From 1686
to 1972 South Carolina was adversely affected by tropical
storms or hurricanes 169 times. Fortunately, however, as
we have seen in the last 20 years it is unusual for tropical
storms or hurricanes to make landfall along the South
Carolina coast.
One reason to review the 1975 report was to see if
it could serve as a baseline regarding the possible effects
of climate change. Although we see no direct effects, we
are aware of changes along the South Carolina coast. An
article in The Post and Courier by S. Fretwell in November,
2013, reported that “1200 acres from four primary barrier
islands in the nature preserve north of Charleston” have
been lost to erosion. More loss is expected as “sea levels
are expected to rise up to 5 feet in the Southeast by the
end of this century.” An article in the same newspaper
by B. Petersen, also in November 2013, mentioned that
the species of shrimp caught in local waters is changing
and that there are changes in plants and birds. Similar
environmental changes have been observed by biologists
and naturalists around the world, and we should be vigilant
for changes, particularly of invasive plants and animals.
Forest, Dune and Marsh Vegetation
Maritime forest covers the core of the Island, and
the ERC report divides the forest into five major stand
types: oak-pine, mixed oak-hardwood, palmetto, oak
thicket and wax myrtle thicket. The report also notes that
this is “the most stable ecosystem on Kiawah” because
it “modifies climatic conditions and supports abundant
terrestrial fauna.” In addition, the report also points out
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that the “most important forest type on Kiawah is the wind
pruned maritime thicket. This zone of secondary dune
vegetation protects the interior forest from damaging salt
aerosols, and it is also the final defense against erosional
forces. ... The maritime forest and its understory play
a vital role in the distribution and support of Kiawah's
reptile, amphibian, mammal and bird populations.”