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Soil Table 3: (English) 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 (~182 days) after To
Example:  January 1 = 1;  February 1 = 32;  March 1 = 60, etc.


 
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
AL
Birmingham
65
19
31
213
Montgomery
67
18
31
213
         
AR
Little Rock
64
21
32
214
      
AZ
Phoenix
73
23
33
215
Tucson
70
18
34
216
     
   
       
CA
Los Angeles
64
7
54
 236
Merced
68
25
33
 215
San Diego
64
7
54
 236
             
CO
Colorado Springs
51 
21
36
 218
Denver
52 
22
37
 219
Grand Junction
55
25
32
 214
   
   
       
DC
Washington
57
22
36
218
  
   
       
FL
Appalachio.
70
15
36
218
Jacksonville
71
14
32
214
  
   
       
GA
Atlanta
62
19
32
214
Augusta
65
18
30
212
Macon
67
17
33
215
           
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
           
IA
Des Moines
52
28
35
217
Sioux City
51
29
34
216
               
ID
Boise
53
21
34
216
Idaho Falls
46
23
34
216
   
   
       
IL
Chicago
51
25
37
219
E. St. Louis
57
24
34
216
Urbana
53
26
35
217
  
   
       
IN
Ft. Wayne
53
24
35
217
Indianapolis
55
24
34
216
South Bend
52
25
37
219
  
   
       
KS
Dodge City
57
25
35
217
Topeka
56
26
35
217
  
   
       
KY
Louisville
60
22
33
215

 
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
LA
Lake Charles
70
16
32
214
New Orleans
70
15
32
214
Shreveport
66
19
32
214
     
MA
Portland
48
22
39
221
Plymouth
51
21
43
225
   
   
       
MI
Battle Creek
50
24
35
217
Detroit
50
25
39
221
Sau St. Marie
42
26
40
222
  
   
       
MN
Duluth
41
28
37
219
Int. Falls
39
31
34
216
Minneapolis
47
29
35
217
  
   
       
MO
Columbia
57
24
35
217
Kansas City
58
26
35
217
Springfield
58
23
34
216
     
MS
Biloxi
70
17
32
214
Columbus
65
19
32
214
Jackson
67
18
31
213
       
MT
Billings
49
23
37
219
Great Falls
48
23
36
218
Missoula
46
21
32
217
           
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
  
   
       
NB
Grand Junction
52
27
35
217
Lincoln
53
28
34
216
N. Platte
51
26
35
217
       
NC
New Bern
 65
 17
35
217
Greensboro
60
20
31
213
               
ND
Bismark
44
31
33
215
Grand Forks
42
33
35
217
Williston
45
29
34
216
               
 NJ
Trenton
55
22
38
220
  
   
       
 NM
Albuquerque
59
22
31
213
Roswell
63
22
30
212
   
   
       
 NY
Albany
50
25
38
220
Binghamton
48
24
38
220
Niagara Falls
50
24
24
216
Syracuse
50
24
38
220
     
NV
Ely
47
22
35
217
Las Vegas
69
23
32
214
Winnemucca
52
22
33
215

 
 
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
OH
Akron
52
23
37
219
Columbus
55
22
34
216
Dayton
56
24
35
222
Toledo
51
25 
36 
218
     
OK
Altus
65
24
33
215
Oklahoma City
62
23
34
216
Tulsa
62
23
34
216
  
            
OR
Astoria
53
9
45
227
Medford
55
17
34
216
Portland
54
13
37
219
     
PA
Middletown
55
23
35
217
Philadelphia
55
22
34
216
Pittsburg
52
23
36
218
Wilkes-Barre
52
23
36
218
      
SC
Charleston
66
16
32
214
Greenville
62
19
33
215
Sumpter
65
18
32
214
   
   
       
SD
Huron
47
30
35
217
Rapid City
50
25
38
220
           
State
City Tm (oF) As(oF) Coldest
Day of Year
To(Days)
(# 1-365)
Warmest
Day of Year
T1(Days)
(# 1-365)
               
TN
Bristol
59
20
32
214
Knoxville
61
21
31
213
Memphis
63
21
32
214
Nashville
60
21
32
214
     
TX
El Paso
66
20
28
210
Ft. Worth
68
21
34
216
Houston
71
16
33
215
San Antonio
72
16
32
214
   
   
       
UT
Salt Lake City
53
24
35
217 
     
VA
Norfolk
61
20
37
219
Richmond
60
19
33
215
Roanoke
59
20
33
215
        
VT
Burlington
46
26
37
219
      
WA
Moses Lake
53
23
29
211
Seattle
53
12
36
218
Spokane
49
21
32
214
           
WI
Green Bay
46
26
37
219
Madison
49
27
36
218
             
WV
Charleston
58
20
33
215
Elkins
52
20
32
214
         
WY
Casper
49
24
37
219
Cheyenne
48
21
39
221
Lander
46
24
38
220
Sheridan
48
24
35
217

 
*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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