26 CHARLOTTEMAGAZINE.COM // JULY 2019
THE BUZZ
NO ONE NEEDS A CLIMATOLOGIST to
explain that Southern summers are foul-
smelling outdoor saunas. But in Piedmont
North Carolina, at least, weather data
reinforce how oppressive humidity can
get, and how mugginess seems to under-
stand when its time has come: July.
July is when air settles over you like
damp cheesecloth. July is when the dew
point, the temperature below which
the air can hold no more water vapor,
can soar north of 70 degrees Fahrenheit,
which makes things generally unbearable.
July is when humidity peaks—the muggi-
est day of the year in Charlotte typically
comes in late July—and you never really
dry o from your morning shower.
The instigator of this misery is what’s
known as the Bermuda High, explains
Brad Panovich, the chief meteorologist
at WCNC. “During most of the year, our
weather generally comes from the north
and west,” he says, as the Bermuda High
parks near the Azores, closer to Europe and
Africa. But starting in late spring, as daysgrow longer and the jet stream
creeps north, the high shis west
to near Bermuda, about 950 miles
east of Charlotte. It conveys warm,
wet air from the south and south-
east up and over the East Coast.
This makes us sweaty and misera-
ble. Its position in late summer also allows
it to ing intense tropical storms along the
Atlantic Coast and into the Gulf of Mexico.
(The Bermuda High is kind of a jerk.)
But like an unwanted houseguest who
nally decides to crash at someone else’s
place, it usually slides back east around
mid-September as the jet stream eases
south—usually. Last year, it hung around
well beyond then, which caused the
warmest and dankest September on
record. Meteorologists consider a dew
point of 70 or higher a signpost of “oppres-
sive” mugginess. Charlotte averages about
100 hours of those in a typical September.
The city experienced more than 500 hours
of them in September 2018. “The night-
time lows never cooled o,” Panovich says.“The air temperature can never
drop below the dew point. So
if you have a high dew point, it
doesn’t cool o at night.”
If you’re wondering why he
places so much emphasis on
dew point instead of the tradi-
tional metric of relative humidity: It’s a
more reliable measure of how uncomfort-
ably sticky the air is. The “relative” in “rela-
tive humidity” refers to air temperature,
which of course uctuates. “Dew point
is more static, more uniform. It stays the
same regardless of temperature,” he says.
“If I tell you the relative humidity is 100
percent, and it’s 20 degrees outside, no
one’s going to tell you it’s muggy. But if it’s
50 percent humidity, and it’s 90 degrees
outside, that’s a muggy day.”
Fortunately, our weather expert keeps
a lengthy list of anti-humidity tactics.
“The only thing you really can do is
have a good air conditioner,” Panovich
says. “Thank God for air conditioning.”
— Greg Lacour ROB DONNELLYWEATHERSTEAM EDUCATION
July is when dew points spike, hair frizzes, and you perspire.
Brad Panovich explains how and whyMARK YOUR
CALENDARS
JULY 24
is historically
the muggiest
day of the year