6 BULLETIN 1309, U. S. DEPARTMENT OF AGRICULTURE 
Table 3. — Maximum, minimum, and mean monthly temperatures, etc. — -Continued 
Month 
1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
Aver- 
age 
Minimum: 
23 
8 
17 
6 
12 
-2 
10 
7 
11 
-2 
20 
12 
-3 
18 
4 

-7 
16 
10 
18 
5 
12 
March . .._ .. 
17 
32 
41 
42 
10 
25 
37 
46 
21 
30 
41 
48 
14 
31 
42 
46 
24 
29 
39 
50 
20 
28 
37 
46 
26 
22 
43 
51 
16 
29 
34 
50 
26 
29 
43 
49 
23 
31 
39 
53 
19 
15 
36 
55 
April ----- 
1912 
1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
Mean monthly: 
July 
76.3 
77.4 
76.5 
76.3 
79.0 
78.0 
75.1 
77.2 
74.3 
78.9 
77.0 
76.9 
August ... .- . . _ . 
74.5 
74.5 
77.2 
74.2 
76.8 
77.1 
77.3 
73.3 
74.9 
72.5 
73.5 
75.1 
September .- - 
71.0 
67.8 
65.1 
71.4 
68.4 
65.2 
64.2 
69.3 
68.8 
74.0 
71.2 
68. & 
October.. 
59.9 
59.5 
58.7 
59.4 
58.0 
51.7 
59.3 
63.8 
60.2 
55.6 
60.1 
58.7 
November .. 
45.7 
46.8 
43.4 
46.8 
47.3 
42.1 
44.5 
46.5 
44.3 
46.5 
48.3 
45.7 
December 
39.6 
39.1 
32.7 
35.0 
35.5 
27.2 
38.8 
31.2 
37.6 
36.6 
37.6 
35.5 
1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
Mean monthly: 
January 
43.9 
37.2 
34.4 
39.3 
34.6 
23.3 
36.8 
27.1 
35.1 
29.8 
36.0 
34.3 
February 
36.3 
28.5 
38.4 
34.5 
33.3 
34.7 
36.2 
31.4 
37.7 
35.6 
32.8 
34.5 
March . 
48.9 
38.5 
38.7 
38.3 
43.7 
46.9 
46.3 
43.6 
55.6 
44.4 
45.6 
44.6 
April 
55.3 
52.5 
58.6 
52.5 
54.7 
53.0 
53.1 
51.2 
59.6 
55.2 
54.0 
54.5 
May 
66.5 
65.4 
62.9 
67.3 
60.3 
69.3 
64.3 
59.0 
62.3 
67.6 
63.7 
64.4 
June. -------- 
73.1 
73.5 
70.6 
70.7 
73.9 
71.4 
74.1 
70.5 
74.0 
75.1 
76.2 
73.0 
Average 
57.6 
55.1 
54.8 
55.5 
55.5 
53.3 
55.8 
53.7 
57.0 
56.0 
56.3 
55.5 
Table 4 shows the date of the last frost in spring and the first frost 
in fall, together with the length of the frost-free period, in the years 
1912-1923, inclusive. The average frost-free period is 195 days. Late 
spring frosts do not often injure small-grain crops in this locality. 
Table 4. — Dates of late spring and early fall killing frosts and length of frost-free 
period at the Arlington Experiment Farm in the 12-year period, 1912- 
inclusive 
Last frost in 
spring 
First frost in fall 
Frost- 
Year 
Date 
Tem- 
pera- 
ture 
Date 
Tem- 
pera- 
ture 
free 
period 
1912 
Apr. 9 
-. do. .- 
O jp 
30 
32 
32 
30 
31 
29 
32 
32 
29 
31 
32 
31 
Nov. 3 
Oct. 22 
Oct. 29 
Nov. 4 
-.do 
Oct. 7 
Oct. 23 
Nov. 9 
Oct. 30 
Oct. 14 
Oct. 21 
Nov. 2 
o p 
32 
31 
31 
31 
32 
32 
32 
32 
29 
31 
32 
26 
Days 
207 
1913 
195 
1914. 
Apr. 14 
Apr. 5 
Apr. 11 
Apr. 15 
Apr. 14 
Apr. 27 
Apr. 15 
Apr. 11 
Apr. 25 
Apr. 10 
197 
1915 - 
212 
1916 
206 
1917 _ _. 
174 
1918 
191 
1919 
195 
1920 
197 
1921 
185 
1922 
178 
1923 
205 
Average 
Apr. 14 
Oct. 27 
195 
