NWS Houston, Texas
September 2017
Regional Climate Summary
Regional Climate Summary
Produced by Nikki Hathaway & Paul Lewis
. . . A Dry September Contrasted the Wet Year-to-Date . . .
Much below normal rainfall occurred across Southeast Texas during
the month of September 2017. However little impacts were noted
since the month began with very wet soils and lingering flooding from
Tropical Storm Harvey's rainfall at the end of August. Therefore, no
drought conditions were experienced across SE Texas throughout
September. Other than a two-week period of cool conditions following
the season's first real cold front on the 5
th
and 6
th
, September ended
with temperatures at or slightly above normal for the month.
1
Photo taken by NWS Meteorologist Kathleen Magee
Precipitation
2
The dry month of September was in stark contrast to the wet year-to-date
by the end of the month. The first day of decent rainfall (more than just a
few tenths), did not occur until September 18
th
. The upper level high
pressure that was over the region began to weaken allowing for an
increase in moisture. Additionally, a trough developed overhead, which
helped to produce scattered showers and thunderstorms across SE Texas
over the following few days.
On September 28
th
, the help of multiple boundaries from both the sea and
bay breezes, along with other outflow boundaries and daytime heating
allowed scattered showers and thunderstorms to develop. More than a
quarter of an inch of rain fell across all four climate sites on this day.
Site
Total
Precipitation (in.)
Departure from
Normal (in.)
Number of
Thunderstorm Days
Maximum Daily
Precipitation (in./date)
Galveston
(GLS)
0.32 -5.71 1 0.31 29th
Houston
Hobby
(HOU)
3.75 -1.46 4 1.32 18th
City of
Houston
(IAH)
1.23 -2.89 5 0.48 20th
College
Station
(CLL)
0.98 -2.20 1 0.76 28th
Precipitation
3
Houston
Galveston
College Station
The following table list those first- and second-order sites which had nine-
month rainfall near or above 90 percent of the normal annual rainfall
through September 30
th
.
Rainfall Dep from Percent of Normal
Climate Site (inches) Annual Norm Annual Rainfall
Angleton/Lake Jackson * 47.02 - 3.84 92.4 percent
City of Galveston 50.77 + 0.01 100.0
City of Houston 72.05 +22.28 144.8
College Station 45.14 + 5.08 112.7
Conroe Airport 55.43 + 6.94 114.3
DW Hooks 66.93 +16.45 132.6
Hobby Airport 70.87 +16.22 129.7
Huntsville Airport 55.70 + 9.56 120.7
Palacios 39.81 - 4.78 89.3
Pearland 73.59 +20.90 139.7
Sugar Land 70.09 +20.61 141.7
* Note: Angleton/Lake Jackson Airport has missing data from August 30th
through September 13th.
4
Precipitation
Nine-month rainfall amounts ended above the annual normal rainfall for
many of the major climate and COOP sites across Southeast Texas.
The following table list those COOP sites which had nine-month rainfall near
or above 90 percent of the normal annual rainfall through September 30
th
.
Rainfall Dep from Percent of Normal
COOP Site (inches) Annual Norm Annual Rainfall
Baytown 92.78 +32.86 154.8 percent
Bellville 6 NNE 47.61 + 5.89 114.1
Brenham 44.50 - 0.64 98.6
Caldwell 44.68 + 5.18 113.1
Cleveland 70.52 +16.28 130.0
Columbus 52.96 + 9.03 120.6
Conroe (COOP) 66.58 +17.81 136.5
Crockett 44.86 - 0.32 99.3
Cypress 61.76 +14.92 131.9
Freeport 2 NW 47.65 - 1.92 96.1
Houston-North Houston 65.94 +13.90 126.7
Houston-Westbury 72.27 +20.45 139.5
Huntsville (COOP) 61.14 +12.06 124.6
Katy Wolf Hill 68.87 +23.34 151.3
Liberty 83.26 +22.01 135.9
Montgomery 57.27 +10.50 122.5
New Caney 2 E 52.38 - 1.11 97.9
NWS League City 85.26 +28.45 150.1
Richmond 69.75 +20.67 142.1
Somerville Dam 40.04 + 1.37 103.5
Thompsons 3 WSW 49.73 + 1.95 104.1
Washington State Park 51.82 +10.14 124.3
Wharton 53.03 + 5.82 112.3
5
Precipitation
Temperatures
6
Average daily temperatures started off around normal for the first
few days of September. Lingering cloud cover from Tropical Storm
Harvey allowed for a break from the summer heat. By the end of the
first week of September, the first strong frontal passage of the
season pushed through SE Texas dropping temperatures roughly five
degrees below normal. Cooler, unseasonable temperatures persisted
through the second week of September. By September 16
th
,
temperatures were back above normal and the warmth continued
through the remainder of the month. This extended period of
summer-like weather brought the departure from average
temperature back up to above normal for the month of September.
Site
Average
Temp
(°F)
Average
High Temp
(°F)
Average
Low Temp
(°F)
Departure
From
Normal (°F)
Maximum
Temperature
(°F)
Minimum
Temperature
(°F)
Galveston
(GLS)
83.2 88.7 77.8 +1.6 92 70
Houston
Hobby
(HOU)
82.1 91.2 73.0 +2.0 95 64
City of
Houston
(IAH)
79.8 89.9 69.7 0.0 93 60
College
Station
(CLL)
80.1 89.9 70.2 +0.1 94 60
Temperatures (Continued)
9
Below is a line graph of temperature trends for the four primary climate sites,
as well as a bar graph comparing above and below normal temperature days
throughout the month of September.
Temperatures
10
Average temperatures were very warm across Southeast Texas
through the end of September. As a matter of fact, 2017 is the
warmest year-to-date through September 30
th
on record for three of
the four first-order climate sites. The following table lists the top-
ten warmest first nine months of the year on record for the City of
Houston and the City of Galveston (with ten or less missing days of
data each year):
Top-10 Warmest 9-Month Average Temperatures
January 1st through September 30th
City of Houston... City of Galveston...
9-Month 9-Month
Rank Ave Temp Year Rank Ave Temp Year
1 74.9 2017 1 76.6 2017
tie 2012 2 76.3 2012
tie 2011 3 74.9 2000
4 74.4 1911 4 74.8 2006
5 74.3 1962 5 74.6 2005
6 73.8 2009 6 74.4 1999
tie 1907 7 74.1 1995
8 73.7 1954 8 74.0 2016
tie 1953 tie 1927
tie 1927 tie 1876
Temperatures
11
The following table lists the top-ten warmest first nine months of the
year on record for Hobby Airport and College Station (with ten or
less missing days of data each year):
Top-10 Warmest 9-Month Average Temperatures
January 1st through September 30th
Hobby Airport... College Station...
9-Month 9-Month
Rank Ave Temp Year Rank Ave Temp Year
1 75.8 2017 1 75.0 2011
2 75.2 2011 2 74.5 2012
3 75.1 2012 tie 1911
4 74.8 1998 4 74.1 2017
5 74.7 2000 tie 1925
6 74.5 2016 6 73.7 2009
7 74.2 2009 7 73.3 2000
tie 1999 8 73.1 2006
9 73.9 2008 9 72.9 1990
10 73.7 2006 tie 1916
tie 2005
SE TX Climate Sites
12
The following table lists the preliminary monthly temperature and
rainfall data for climate sites across Southeast Texas in addition to
the COOP site at the League City National Weather Service office.
These climate sites all report hourly data besides the COOP site at the
League City National Weather Service site HGX.
13
The following table lists the rainfall data from the volunteer network
of COOP observers. Note that some of these numbers are
incomplete and may be updated at a later date. Year-to-date totals
reflect any updates to previous months during the year.
CO-OP Observer Sites – p. 1 of 3
14
The following table lists the rainfall data from the volunteer network
of COOP observers. Note that some of these numbers are
incomplete and may be updated at a later date. Year-to-date totals
reflect any updates to previous months during the year.
CO-OP Observer Sites – p. 2 of 3
CO-OP Observer Sites – p. 3 of 3
15
Notes:
* Current monthly data is unavailable for these sites. The year-to-
date data for these stations have been updated through the end of
the previous month.
# The "Year-to-Date" rainfall data for these sites was impacted by
incomplete August rainfall data which did not include any data for
Tropical Storm Harvey.
& The "Year-to-Date" rainfall data for the following sites was
impacted because of only partial data for Tropical Storm Harvey
in August:
- Eagle Lake Research Center appears to have missed rainfall for
August 26th. The site did have a 4-day total of 19.50 inches for
August 26th-30th.
- The COOP form shows that Lake Livingston missed rainfall for
August 26th and 27th while the 28th-31st were for 1-day totals.
- New Caney 2 E had missing data on August 29th.
- Somerville Dam did not report an observation for August 29th.
- South Madisonville did not report observations for August 25th or
29th. (In addition, South Madisonville did not report any rainfall
for all of June and July.)
Monthly Record Temperature and Rainfall Data
16
There were only two records tied during September 2017—both at
the same site.
Site Date Record Type New Record Previous Record
CLL None
GLS Sep 20
th
High Min Temp
83 Tied 1900
Sep 25
th
High Min Temp
82 Tied 1998 & prev
HOU None
IAH None
Drought Conditions
17
With the previous month of August extremely wet due to the widespread heavy
rainfall from Tropical Storm Harvey, SE TX remained clear from drought conditions
over the past few weeks. The month of September reaped the benefits of saturated
top soil and a lengthy departure from abnormal dryness. As a result, there were no
drought conditions or impacts noted across the entire area of SE Texas, though the
top soil has continued to dry out throughout the last month. As a result, an absence
from drought criteria will not last long into October. The following table lists the
abnormal dry or drought conditions as well as the counties impacted, as noted by
the U.S. Drought Monitor.
For the week ending on: Intensity and Impacts
Impacting the
following Counties
September 5
th
No Drought Conditions None
September 12
th
No Drought Conditions None
September 19
th
No Drought Conditions None
September 26
th
No Drought Conditions None
Most Recent Drought Map
Posted: September 26
th
Source:
http://droughtmonitor.unl.edu
October Outlook
18
The latest outlook from the Climate Prediction Center (CPC) calls for an
increased likelihood of above normal temperatures and near normal
precipitation for the month of October.
Upcoming Temperature Outlook Upcoming Precipitation Outlook
Site
Normal Monthly
Precipitation (in.)
Galveston (GLS) 5.52
Houston Hobby (HOU) 5.99
City of Houston (IAH) 5.70
College Station (CLL) 4.91
Site
Average
Temp(°F)
Normal
High (°F)
Normal
Low (°F)
Galveston
74.3 68.1 80.6
Houston
Hobby
72.1 63.1 81.2
City of
Houston
71.5 60.9 82.0
College
Station
70.8 60.3 81.4
Climate Primary Site History
19
Galveston (GLS)
Houston Hobby (HOU)
City of Houston (IAH)
College Station (CLL)
Records for Galveston are from observations at the following locations: 67-69
Strand (April 1, 1871 - Aug 31, 1874); 23rd and the Strand (Sep 1, 1874 - July 29,
1878), 1.75 miles WSW of the previous location; the Custom House at Bath Street
and the Strand (July 30, 1878 - May 8, 1882); Colorado and Sante Fe Railroad
Building at 25th and the Strand (May 9, 1882 - March 14, 1883); back to the
Custom House which later became the Cotton Exchange Building (March 15, 1883 -
June 24, 1898), about a 1/3 of a mile E of the previous Custom House location; The
Levy Building at 2223 Market Street (June 25, 1898 - Nov 26, 1900); the Trust
Building at Tremont and Post Office Streets (Nov 27, 1900 - June 24, 1946), one-
quarter mile south of the Levy Building; the U.S. Post Office Building at 601
Rosenberg (June 25, 1946 - 1994); Scholes Field (January 1995 to present).
Records from 1893 through July 1951 are based on observations taken at the Texas
Agriculture Experiment COOP Station main farm located 6 miles southwest of
College Station. Records from August 1951 through the present are based on
observations taken at Easterwood field. Normal temperatures are calculated from
1981 to 2000 period.
Records are based upon observations beginning in August 1931.
Records for the City of Houston are from observations at the following locations:
Cotton Station from July 1881 through September 1909, Stewart Building at Preston
and Fannin from September 1909 through February 1926, Shell Building at Texas
and Fannin from March 1926 through August 1938, Federal Building at Franklin
and Fannin from August 1938 through May 1969, Intercontinental Airport from
June 1969 to the present
