Colorado Climatology 
11 
LIKELY DATES OF LAST KILLING FROST 
The average date at which the last killing frost is likely 
to occur in a locality as a normal event, must often determine 
the limit in latitude and altitude at which a fruit or certain 
kinds of crops can be grown. Even in the most favored fruit 
regions of the State the records bring out the fact that killing 
frosts may be expected and will occasionally do great damage, 
though the smudge pot is lessening the danger and making a 
certainty of many years that formerly would have proved a 
total loss of crop. At Fort Collins the average date is May 10 
to May 15 and September 15 to 20. At Rocky Ford and Chey¬ 
enne Wells the season is a little longer. 
In reporting the meteorological observations for the last 
twenty-five years it has been thought well to include, for pur¬ 
pose of comparison, the records taken for temperature and 
rainfall for our substations, and also the precipitation from a 
number of stations scattered over the State. Some of these 
observers reported to this Station during the early years, but 
during the last few years have reported altogether to the 
United States Weather Bureau office in Denver. They have 
been included here that they may be accessible to people who 
may he interested along with data from our Station. 
LOCATION OF STATION 
The Agricultural Experiment Station at Fort Collins is 
located at the base of the Rocky Mountains, about four miles 
from the lowest foothills, bejmnd which the mountains rise to 
the summit of the range about fifty miles westward. It is lo¬ 
cated in Larimer county, about seventy-five miles north of 
Denver, on bench land about one mile south of and 40 feet 
above Cache la Poudre river. The College is in an irrigated area 
which extends about three miles westward, while in all other 
directions there are irrigated lands for a number of miles. The 
nearness to the mountains affects the climate in the amount 
and character of the clouds, in the temperature and in the di¬ 
rection and character of the winds. The elevation is about 
5,000 feet, the latitude 40° 34', and the longitude 105° 6' west 
of Greenwich. 
EQUIPMENT USED 
The maximum and minimum thermometers used are called 
self-registering, that is, the maximum thermometer registers 
the warmest temperature of the day and the minimum the 
coldest and the thermometers remain at the extreme point un¬ 
til read and reset. They are read each day so that a continuous 
