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Soil Table 3: Mean Earth Temperatures,
Annual Soil Swing, and Phase Constants for U.S. Cities*

Note: The 'Phase Constant' represents the coldest day of the year.
The warmest day of the year is approximately 6 months (180 days) after To.



State

City

Tm (oF)

As(oF)

To(Days)

 

 

 

 

 

AL

Birmingham

65

19

31

 

Montgomery

67

18

31

 

 

 

 

 

AZ

Phoenix

73

23

33

 

Tucson

70

18

34

 

 

 

 

 

AR

Little Rock

64

21

32

 

 

 

 

 

CA

Los Angeles

64

7

54

 

Merced

68

25

33

 

San Diego

64

7

54

 

 

 

 

 

CO

Colorado Springs

51

21

36

 

Denver

52

22

37

 

Grand Junction

55

25

32

 

 

 

 

 

DC

Washington

57

22

36

 

 

 

 

 

FL

Appalachico.

70

15

36

 

Jacksonville

71

14

32

 

 

 

 

 

GA

Atlanta

62

19

32

 

Augusta

65

18

30

 

Macon

67

17

33

 

 

 

 

 

ID

Boise

53

21

34

 

Idaho Falls

46

23

34

 

 

 

 

 

IL

Chicago

51

25

37

 

E. St. Louis

57

24

34

 

Urbana

53

26

35

 

 

 

 

 

State

City

Tm (oF)

As(oF)

To(Days)

 

 

 

 

 

IN

Fort Wayne

53

24

35

 

Indianapolis

55

24

34

 

South Bend

52

25

37

 

 

 

 

 

IA

Des Moines

52

28

35

 

Sioux City

51

29

34

 

 

 

 

 

KS

Dodge City

57

25

35

 

Topeka

56

26

35

 

 

 

 

 

KY

Louisville

60

22

33

 

 

 

 

 

LA

Lake Charles

70

16

32

 

New Orleans

70

15

32

 

Shreveport

66

19

32

 

 

 

 

 

MA

Portland

48

22

39

 

 

 

 

 

MS

Plymouth

51

21

43

 

 

 

 

 

MI

Battle Creek

50

24

35

 

Detroit

50

25

39

 

Sau St. Marie

42

26

40

 

 

 

 

 

MN

Duluth

41

28

37

 

Int. Falls

39

31

34

 

Minneapolis

47

29

35

 

 

 

 

 

MS

Biloxi

70

17

32

 

Columbus

65

19

32

 

Jackson

67

18

31

 

 

 

 

 

MO

Columbia

57

24

35

 

Kansas City

58

26

35

 

Springfield

58

23

34

 

 

 

 

 

State

City

Tm (oF)

As(oF)

To(Days)

 

 

 

 

 

MT

Billings

49

23

37

 

Great Falls

48

23

36

 

Missoula

46

21

32

 

 

 

 

 

NB

Grand Junction

52

27

35

 

Lincoln

53

28

34

 

N. Platte

51

26

35

 

 

 

 

 

NV

Ely

47

22

35

 

Las Vegas

69

23

32

 

Winnemucca

52

22

33

 

 

 

 

 

NJ

Trenton

55

22

38

 

 

 

 

 

NM

Albuquerque

59

22

31

 

Roswell

63

22

30

 

 

 

 

 

NY

Albany

50

25

38

 

Binghamton

48

24

38

 

Niagara Falls

50

24

24

 

Syracuse

50

24

38

 

 

 

 

 

NC

New Bern

65

17

35

 

Greensboro

60

20

31

 

 

 

 

 

ND

Bismark

44

31

33

 

Grand Forks

42

33

35

 

Williston

45

29

34

 

 

 

 

 

OH

Akron

52

23

37

 

Columbus

55

22

34

 

Dayton

56

24

35

 

Toledo

51

25

36

 

 

 

 

 

State

City

Tm (oF)

As(oF)

To(Days)

 

 

 

 

 

OK

Altus

65

24

33

 

Oklahoma City

62

23

34

 

Tulsa

62

23

34

 

 

 

 

 

OR

Astoria

53

9

45

 

Medford

55

17

34

 

Portland

54

13

37

 

 

 

 

 

PA

Middletown

55

23

35

 

Philadelphia

55

22

34

 

Pittsburg

52

23

36

 

Wilkes-Barre

52

23

36

 

 

 

 

 

SC

Charleston

66

16

32

 

Greenville

62

19

33

 

Sumpter

65

18

32

 

 

 

 

 

SD

Huron

47

30

35

 

Rapid City

50

25

38

 

 

 

 

 

TN

Bristol

59

20

32

 

Knoxville

61

21

31

 

Memphis

63

21

32

 

Nashville

60

21

32

 

 

 

 

 

TX

El Paso

66

20

28

 

Ft. Worth

68

21

34

 

Houston

71

16

33

 

San Antonio

72

16

32

 

 

 

 

 

UT

Salt Lake City

53

24

35

 

 

 

 

 

VT

Burlington

46

26

37

 

 

 

 

 

State

City

Tm (oF)

As(oF)

To(Days)

 

 

 

 

 

VA

Norfolk

61

20

37

 

Richmond

60

19

33

 

Roanoke

59

20

33

 

 

 

 

 

WA

Moses Lake

53

23

29

 

Seattle

53

12

36

 

Spokane

49

21

32

 

 

 

 

 

WV

Charleston

58

20

33

 

Elkins

52

20

32

 

 

 

 

 

WI

Green Bay

46

26

37

 

Madison

49

27

36

 

 

 

 

 

WY

Casper

49

24

37

 

Cheyenne

48

21

39

 

Lander

46

24

38

 

Sheridan

48

24

35



*Adapted from Closed-Loop/Ground-Source Heat Pump Systems Installation Guide.  NRECA Research Project 86-1.  Oklahoma State University.  1988. and Perry, Robert H. and Chilton, Cecil H. Chemical Engineer's Handbook. 5th Ed. New York, McGraw Hill Book Company, 1973.


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