REFERENCE MATERIAL

....... -- ,

Climatic Atlas of Texas

LP-192

TEXAS DEPARTMENT OF WATER RESOURCES

DECEMBER 1983

I

CLIMATIC ALTAS OF TEXAS

By

Thomas J. Larkin and George W. Bomar Meteorologists

LP-192

Texas Department of Water Resourc;es

December 1 983

TEXAS DEPARTMENT OF WATER RESOURCES

Charles E. Nemir, Executive DirectOlr

TEXAS WATER DEVELOPMENT BOARD

Louis A. Beecherl Jr., Chairman Glen E. Roney

George W. McCleskey, Vice Chairman Lonnie A. "Bcl" Pilgrim

W. O. Bankston Louie Welch

TEXAS WATER COMMISSION

Felix McDonald, Chairman Lee B. M. Biggart, Commissioner Ralph Roming. Commissioner

Authorization for use or reproduction of any original material contained in this publication. i. e., not obtained from other sources, is freely granted fhe Department would appreciate acknowledgement.

Published and distributed by the

Texas Department of Water Resources Post Office Box 13087 Austin, Texas 78711

ii

PREFACE

Climatological data is published in the form of tables wlith columns of numbers that indicate average conditions for a designated place. These data arE~ used to define climate in terms of precipitation, temperature, evaporation and wind-the primary components of climatic descrip-tion. However, the use of rows and columns of numbers is awkward when trying to visualize and interpret the relative changes of climatic components over CI large area. The purpose of this atlas is to illustrate the statewide distribution of these primary Giimatic components. This is accom-plished by.contour analysis of data points on state maps that delineate county shapes and show county names. These maps depict long-term averages of monthly and annual climatic conditions. The maps were analyzed by Department meteorologists.

The authors of this atlas wish to thank the Chief of the Weather and Climate Section, Robert F. Riggio, for his guidance and William H. Hanshaw for plotting the data; Bobbie R. Critendon in Surface Water Data for his review of the evaporation analyses; Data Systems staff members Carl A. Johnson and Marion H. Porterfor developing the computHr-generated wind roses; and Graphic Arts staff members Carey E. Johnson and Ellen A. Wadsworth for drafting the contour maps.

iii

ABSTRACT

Climate is the history of weather and is defined by the long-term averages of atmospheric variables such as precipitation, temperature, evaporation and wind. This atlas identifies "aver-age" conditions of these four major components of climate through a series of maps and wind

roses.

The maps depict the statewide distribution of monthly and annual values of average precipi-tation. average temperature. and average gross lake surface evaporation rates. Wind roses show the frequency of occurrence of average wind direction and speed in selected cities across the State.

iv

TABLE OF CONTENTS

Page

PREFACE. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . iii

ABSTRACT . .............................................................. t . iv

INTRODUCTION . ...................... " ................ " . . . . . . . . . . . . . . . . . . . . . . 1

AVERAGE PRECIPITATION . ......................... " . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Definition of Terms. . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 4

Source of Data ............................................................ 4

Period of Record. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Average Monthly Precipitation Maps. . . . . . . . . . . . . . . . . .. . . . .. . . . .. . . . . . . . . . . . . . 5

January............................ ............................ ........... 6

February. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

March.................................................................... 8

April...................................................................... 9

May...................................................................... 10

June. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . .. . . . .. . .. . . . .. . .. . . . .. . .. . . 11

July............................................ ........................... 12

Aug ust ........................................ " . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3

September .................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

October................................................................... 15

November. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

December .............................................. " ......... " . .. .. . 17

v

TABLE OF CONTENTS-Continued

Page

Average Annual Precipitation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 18

AVERAGE TEMPERATURE.. . .. . .. .. . .. . . .. . .. . . . . .. .. .. .. . . . .. . .. .. . .. .. . .. .. . 19

Definition of Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 19

Source of Data .............................................................. 19

Period of Record. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Average Monthly Low Temperature Maps ...................... ".............. 21

January .................................................... " . .. . . . . . . . . . . . 22

February. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

March.................................................................... 24

April...................................................................... 25

May...................................................................... 26

June...................................................................... 27

July....................................................................... 28

August.................................................................... 29

September . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

October. .......... ............... ......................................... 31

November. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

December. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Average'Monthly High Temperature Maps.. . .. . . . .. . . . . . . . . . . . . . . .. . .. . . . . . . . . 35

January. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . 36

February. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

March............... .................... ................................. 38

April................. ............................ ........................ . 39

vi

TABLE OF CONTENTS-Continued

Page

May...................................................................... 40

June ...................................... " . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 41

July....................................................................... 42

August.................................................................... 43

September ........................................................... I 44

October........................................ .. ........ ................. 45

November............ .................... ..... ...... ....................... 46

December. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . . . . . . . . . .. . . . . . 47

Average Annual Low Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . 48

Average Annual High Temperature. .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . 49

Average Annual Temperature. . . . . . . . . . . . .. . . . . . .. . . . .. . . . .. . . . . . . . . . . . . . . . . .. 50

AVERAGE GROSS LAKE SURFACE EVAPORATION RATES. . . . . . . . . . . . . . . . . . . . 51

Definition of Terms. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Source of Data .............................................................. 51

Period of Record. . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Average Monthly Gross Lake Surface Evaporation Rate Maps. . . .. . . . . . . . . . . . . . . 53

January......................................................... .......... 54

February. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .