4 BULLETIN 1026, U. S. DEPARTMENT OF AGRICULTURE. 
Table 1. — Summary of meteorological records at Fort Collins. Colo.. 1887-1917.° 
Month. 
Rainfall 
(inches.). 
Temperature 
(°F.). 
Wind (Diiles per 
hour). 
Monthly 
mean. 
1 
y. 
a 
S 
o 
- 
= 
o 
JQ 
§ 
< 
25.9 
71.0 
26. 7 
70.0 
35.7 
SO. 3 
46.1 
91.0 
53.9 
90.0 
63.1 
94.2 
6*. 1 
99.9 
67.2 
99.6 
59.2 
95.0 
47.7 
8S.0 
36.0 
78.0 
28.0 
6S.0 
Monthly 
mean. 
I I £ ■ 
a i i 
Evaporation 
'. inches;. b 
EE 
EE 
E 
= 
January 
February. . . 
March 
April 
May 
June 
July 
August 
September.., 
October 
November. . 
December . . 
. 0.35 
. .62 
. 1.05 
. 2.16 
.i 3.06 
■ 1-48! 
. 1.S2 ; 
. 1.23 ; 
. 1.29 ! 
. 1.12 
. .40 
. .46 
2.32 
1.65 
3. 35 
10.56 
7.47 
3.65 
4.95 
3.14 
3. OS 
3.23 
1. SO 
4.08 
0.01 
.03 
.00 
.05 
.60 
.03 
.17 
.16 
.00 
-31. 4 
-38. 4 
-24.6 
5.1 
12.1 
31.2 
36.0 
31.7 
22.0 
- 8.0 
-21.1 
-31. 
6.4 
6.9 
10.1 
10.4 
11.9 
12.3 
10.9 
9.6 
7.0 
6.4 
7.2 
9.1 
9.4 
10.2 
4.0 
4.4 
4.7 
5.9 
4.7 
4.5 
71.3 
72.5 
67.1 
59. 7 
63.4 
.2 
3. 5 I 67. 2 
3.3 I 67.9 
2. 8 j 69. 8 
3. 4 72. 3 
1.23 
1.45 
2.63 
4.21 
4.6S 
5.42 
5.59 
5.07 
4.30 
3.28 
1.56 
1.17 
-, 
2.64 
3. 23 
4.60 
6.17 
6.63 
7.70 
7.32 
6.57 
5. 57 
4.64 
2.81 
1.88 
0.68 
.58 
.57 
2.24 
3.49 
3.97 
4.26 
3.79 
3.14 
2.17 
.62 
.26 
Year . 
15.04 22.49 
11 46. 5 i 99. 
-3S.4 6.3 9.3 4.7 67.4 40.59 47.30 34.24 
a All meteorological records pertaining to Fort Collins were taken from Colorado 
periment Station Bulletin No. 245. Colorado Climatology, by Robert E. Trimble, 1918. 
& From tanks 3 by 3 feet deep. Water surface about 2 inches above ground. 
Ex- 
Approximately two-thirds of the rainfall comes during the grow- 
ing season, from April 15 to September 15. An average of 74 days 
of the year shows precipitation, mostly in the form of light showers 
and snows, though rains of more than 0.5 inch usually occur several 
times during the season. Heavy local rains or cloudbursts occasion- 
ally do some damage to crops and canals, but in general they are 
rather a benefit, as they flood the streams and afford additional water 
for irrigation and storage. At Greely 2 the average rainfall is about 
2 inches less than at Fort Collins, but the seasonal distribution is 
about the same. In the mountainous section of the Cache la Poudre 
drainage area the rainfall is heavier and averages perhaps 22 inches 
annually. There is a rather notable range of temperature in the valley. 
At Greeley temperatures of 103 c above and 45 c below zero have been 
recorded, giving an absolute range at that point of 148°. At Fort 
Collins the mean temperatures for January and for July differ by 10°. 
and the daily range is approximately 30°. but warm chinooks from 
the west or cold waves from the north often produce a change of as 
much as 40° within 2 or 3 hours. In general, the extremes of tem- 
perature last only a short time, and the impression of the climate 
which remains is one of crisp dry air. clear skies, and warm sunlight. 
At Fort Collins the average period between killing frosts is 144 days. 
1 Meteorological records for Greeley were furnished by F. H. Brandenburgm, U. S. 
Weather Bureau, Denver. 
