Omaha daily bee., 1918-05-30
Nebraska s. General Climatic Conditions
BY GEORGE A. LOVELAND,
In Charge Weather Bureau Experiment Station.

Nebraska is in the general path of the low
pressure, or storm, areas that move across
the United States from west to east The
important factors in determining its climate
are, first, the distance from the equator, be-
cause the heat received from the sun is
greater at the equator and decreases north
ward; second, the altitude, or elevation above
sea level, because the higher locations have
lower temperature; third, the distance and
direction from the Iulf of Mexico and the
Atlantic ocean, because the supply of mois-
ture from rain and snow comes mainly from
these larger bodies of water; fourth, the
Rocky mountains, located near the western
boundary, because they have an important
effect upon both temperature and moisture
January is the coolest month, with a mean
temperature of Is degrees in the southeast
and 20 degrees, or little below, in the north
February is almost as cold, averaging about
3 degrees warmer, while December is next
with an average of but degrees higher than
February While the coldest weather Of the
year may occur in any of these three winter
months, it is most likely to occur in January,
and it most frequently occurs in the last half
of that month. In the coolest days of winter
the temperature usually falls to between 10
and 20 degrees below zero.
The latest that killing frost has occurred
in most of the state is May 27. This was in
1907, when the freezing temperature covered
most of the southern and eastern counties.
In the northwestern part of the state such
severe frosts have occurred in June, and in
1902 one occurred on June q. The last kill
ing frost, it will be observed, happens as a
rule in the southeastern section in the last
| ten days of April, but comes gradually later
| northward and westward, occurring near
| May in the greater portion of the southern
| and eastern sections and from May 10 to IS
| in the more elevated portions in the north
| and west
The average annual precipitation for the
state as a whole is 1867 inches Most OF
! this is rain, the snowfall for the year averag-
ing only about Is inches, equal to nearly
| two and one-half inches of water or about
| one-tenth the annual precipitation.
The year is divided into wet and dry
seasons. May, June and July constitute the
wet season, with 46 per cent Of the annual
amount, while November, December, January
and February are the four dry months, with
| but II per cent of the normal amount The
other 43 per cent falls during the remaining
FIVE months, or approximately one-tweftf
of the annual amount for each month. As
| this indicates, very little rain or snow falls
during the late fall and winter months, the
average being less than an inch OF water q
month. A slight increase is manifested r
|
when from two to three inches is the norma
for most parts of the state.
| June is the month of heaviest rainfall. I
is also the period when rainfall is most GER
tain-that is, least likely to vary from tn,
average. In an ordinary June rain fails a
one place on eight or nine of the thirty days
This would mean rain every third or fourth
day. This average condition rarely occurs
still, several consecutive days without rain il
| June are unusual
While the average monthly rainfall fo
May and July is nearly the same as that fo
June, there is greater liability to variation
from the average. In May this variation i
less likely to be important, as the tempera
ture is lower than in July and the rainfall i
less likely to occur in heavy showers when
large percentage of the water would run int
the streams without soaking into the ground
Rain falls in May on the average about tn
same number of days as in June, and drout
d periods aye unlikely to occur. In July tn
showers are slightly farther apart, and drout
periods rather more frequent. The decreas
in rainfall after July is rapid The averag
for August is only three -fourths that of July
and for September only three-fourths tina
of August In an average August rain fall
at anv one place on six or seven days. Heav