10 BULLETIN 941, U. S. DEPARTMENT OF AGRICULTURE. 
recorded at Houston, Springfield, and Koshkonong are as follows: 
Winter, 34.5 degrees; spring, 56.1 degrees; summer, 75.4 degrees; 
fall, 58.8 degrees; annual, 56.2 degrees. The area is subject to 
sudden changes in temperature, summer temperatures of 83 degrees, 
84 degrees, and 86 degrees, respectively, having been recorded at 
these stations as early as February, while freezing temperatures have 
been recorded as late as May. Periods of warm growing weather in 
the spring which caused the sap to rise in dormant vegetation, 
followed by freezing weather, have been very disastrous to such fruit 
crops as peaches, and both fruit buds and trees have frequently 
been killed. 
As recorded at five stations, viz, Houston, Mountain Grove, Birch- 
tree, Springfield, and Koshkonong, the average date of occurrence of 
the last killing frost in spring is April 12. In the northern part of 
the area, at Houston, the average date is April 20; in the southern 
part, at Koshkonong, it is April 5. The average date of occurrence 
of the first killing frost in fall as recorded at these five stations is 
October 20. The records kept at these stations show the average 
of the number of days in the growing season to be 183. 
The difference of one degree in latitude between the northern and 
southern parts of the area results in a difference of 26 days in the 
average growing season. Thus, in the lower part of the area spring 
vegetation and grass begin to grow two or three weeks earlier than 
in the northern part, and, consequently, cattle can be turned on 
pasture about two weeks earlier. The grazing period in the fall is 
also longer for the southern area than for the northern; the value 
of this, however, is not so great as the earlier grazing in the spring. 
RAINFALL. 
The rainfall at the five stations, Houston, Mountain Grove, Birch tree, 
Springfield, and Koshkonong, would seem to indicate an abundance 
of rain, the average in inches being as follows: Winter, 7.97; spring, 
12.93; summer, 13.29; fall, 8.88; annual, 43.07. It is seldom, how- 
ever, that the average rainfall and distribution is recorded in any 
particular year. The spring and summer rainfall is the most vital, 
and the distribution of the rainfall is a factor equal in importance 
to the amount. 
The year 1917 was commonly reported as a year favorable to crop 
production, but all farmers interviewed were unanimous in reporting 
that for a number of years prior to 1917 this region was visited by 
disastrous droughts with great resulting damage to crops, especially 
corn, and to pasture. Precipitation records bear out this statement. 
The records kept at the five stations above mentioned show their 
average rainfall for 1917 to have been 41.7 inches, or within 2 inches 
of the average annual rainfall for the region. The distribution was 
