August 2010 Temperatures across the Rio Grande Valley: Deja Vu all over again? Near record heat similar to 2009; humidity makes it feel more oppressive

Average high and low temperatures and all time rankings (preliminary) for August 2010 across Deep South Texas and the Rio Grande Valley(click to enlarge)

Preliminary, unofficial average highs, lows, departures, and rank, for August 2010.

August 2010: South Texas Sauna
Record to Near Record Heat Across Deep South Texas

Overview
What a difference a year didn’t make. After a fairly seasonable summer, perhaps aided by moderate to high soil moisture content left by periodic winter and spring rains, followed by Alex’s torrents and additional rainfall from Tropical Depression #2 to close June and begin July, rainfall became scarce in August with many locations reporting less than an inch total for the month. For much of the month, high pressure (below) through the depth of the atmosphere dominated Texas and northern Mexico. This high, possibly La Canícula (a persistent ridge of high pressure stretching across northern Mexico during the heart of summer), aided the swelter. Unlike in 2009, when summer drought dominated and dew point, or a measure of surface humidity, remained tolerable, August 2010 will be remembered for perhaps more discomfort than 2009 as the heat index, or "feels–like" temperature, routinely exceeded 105°F and often pushed past 110°F, particularly toward the coast mainly east of Federal Highway 281. On top of everything, Brownsville broke a 132 year–old all–time record, with a monthly average of 87.1°F, besting the prior record by nearly a half a degree Fahrenheit!

A brief climate review for August 2010 follows. Additional rainfall information, links, and other data may be provided in the next few weeks.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
511 AM CDT WED SEP 1 2010

...AUGUST 2010 CLIMATE ROUNDUP FOR DEEP SOUTH TEXAS...

RECORD DATES FOR EACH LOCATION ARE AS FOLLOWS:

BROWNSVILLE RECORDS BEGAN 1878...
HARLINGEN RECORDS BEGAN 1911...
MCALLEN RECORDS BEGAN 1941...

.BROWNSVILLE...

THE AVERAGE TEMPERATURE IN BROWNSVILLE FOR AUGUST WAS 87.13
DEGREES...3.1 DEGREES ABOVE NORMAL. THIS IS THE WARMEST AUGUST ON
RECORD...AND THE THIRD WARMEST RECORDED MONTH IN
BROWNSVILLE...BEHIND JUNE 1998 AND JULY 1980. ONE RECORD HIGH
MINIMUM TEMPERATURE WAS SET ON THE 30TH.

BROWNSVILLE AIRPORT RECEIVED 0.92 INCHES OF RAIN IN AUGUST...2.07
INCHES BELOW NORMAL. THIS IS THE 38TH DRIEST AUGUST IN BROWNSVILLE
HISTORY.

.HARLINGEN...

THE AVERAGE TEMPERATURE IN HARLINGEN FOR AUGUST WAS 86.24
DEGREES...1.7 DEGREES ABOVE NORMAL. THIS IS THE 17TH WARMEST AUGUST ON RECORD WHEN COMBINING
THE COOPERATIVE LOCATION WITH VALLEY INTERNATIONAL AIRPORT.
TWO RECORD HIGH MINIMUM TEMPERATURES WERE SET OR TIED ON THE 20TH AND 30TH.

HARLINGEN AIRPORT RECEIVED 0.16 INCHES OF RAIN IN AUGUST...2.76
INCHES BELOW NORMAL. THIS IS THE 8TH WETTEST AUGUST IN
HARLINGEN...AND THE DRIEST AUGUST SINCE 1958.

.MCALLEN...

THE AVERAGE TEMPERATURE IN MCALLEN/MILLER AIRPORT FOR AUGUST WAS 87.98
DEGREES...1.9 DEGREES ABOVE NORMAL. THIS IS THE 7TH WARMEST AUGUST
ON RECORD FOR MCALLEN. THREE RECORD HIGH MINIMUM TEMPERATURES WERE
SET OR TIED ON THE 8TH...15TH...AND 30TH.

MCALLEN AIRPORT RECEIVED 0.26 INCHES OF RAIN IN AUGUST...2.47 INCHES
BELOW NORMAL. THIS IS THE 14TH DRIEST AUGUST ON RECORD.

Daily weather map, August 22nd 2010, showing 500 mb heights across the U.S. and northern Mexico (click to enlarge)

500 millibar heights for Sunday, August 22, just prior to the hottest temperatures of 2010 in Deep South Texas. Note the large high pressure cell across Texas, denoting very hot temperatures. This pattern generally prevailed for much of August 2010.