4 BULLETIN" 1026, U. S. DEPARTMENT OF AGRICULTURE. 



Table 1. — Summary of meteorological records at Fort Collins, Colo., 1887-1917.'^ 



Month. 



Rainfall 

 (inches). 



Monthly 

 mean." 



Temperature 

 CT.). 



Wind (Diiles per 

 hour). 



Monthly 

 mean. 



Evaporation 

 (inches). 6 



36 



Sc 



January . . . 

 February. . 



March 



April 



May 



June 



July 



August 



September. 

 October . . . 

 Novraiber. 

 December. 



Year 



0.35 



.62 



1.05 



2.16 



3.06 



1.48 



1.82 



1.23 



1.29 



1.12 



.40 



.46 



2.32 

 1.65 

 3.35. 

 10.56 



7.47 

 3.65 

 4.95 

 3.14 

 3.08 

 3.23 

 l.SO 

 4.08 



0.01 

 .03 

 .00 

 .05 

 .60 

 .03 

 .17 

 .16 

 .00 



25.9 

 26.7 

 35.7 

 46.1 

 53.9 

 63.1 

 68.1 

 67.2 

 59.2 

 47.7 

 36.0 

 28.0 



71.0 

 70.0 

 80.3 

 91.0 

 90.0 

 94.2 

 99.9 

 99.6 

 95.0 

 88.0 

 78.0 

 68.0 



-31.4 



-38.4 



-24.6 



5.1 



12.1 



31.2 



36.0 



31.7 



22.0 



-8.0 



-21.1 



-31.0 



6.4 

 6.9 



6.9 

 6.0 

 4.8 

 4.7 

 5.1 

 5.7 

 6.0 

 6.5 



10.1 

 10.4 

 11.9 

 12.3 

 10.9 



9.6 



7.0 



6.4 



7.2 



9.1 



9.4 I 

 10.2 I 



4.0 

 4.4 

 4.7 

 5.9 

 4.7 

 4.5 

 3.1 

 3.1 

 3.5 

 3.3 

 2.8 

 3.4 



71.3 

 72.5 

 67.1 

 59.7 

 63.4 

 63.9 

 66.8 

 67.2 

 67.2 

 67.9 

 69.8 

 72.3 



1.23 



1.45 

 2.63 

 4.21 

 4.68 

 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 



15. 04 22. 49 



46.5 



99.9 



-38.4 



6.3 



67.4 



40.59 47.30 i 34.24 



a All meteorological records pertaining to Fort Collins were taken from Colorado Ex- 

 periment Station Bulletin No. 245. Colorado Climatology, by Robert E. Trimble. 191S. 

 6 From tanks 3 by 3 feet deep. Water surface about 2 inches above ground. 



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 ^ 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 Greele}^ temperatures of 103° above and 45° 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 40°, 

 and the dail}^ 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, 



^ Meteorological records for Greeley were furnished by F. 

 Weather Bureau, Denver. 



H. Brandenburgm, U. S. 



