Year: 1865

PecuIiarities of Idaho Climate.


It has been long a weIl-known fact that the
climate of Idaho Territory is but little inAu-
enced by the ordinary conditions of latitude.
The general rule that, as we advance north
ward, the cold increases, does not hold good
in many portions of this country. That the
climate of the whole of the Pacific Coast is
much milder than in the same degree on the
Eastern sea- board, is within the knowledge
and experience of every one who has long
resided here. The cause has never to our
knowledge, been satisfactorily explained.
the country explain the pecuiarities of cl-
mate in certain dstricts-but not of that
universal, uniform temperature pervading the
atmosphere of the whole Coast. Neither has
the philosophy of many of the local peculi-
aritles of temperature, ever been thoroughly
understood-and among them, the climate of
Idaho.


Capt. Mullen, in his Explorations and Re-
port on the wagon road route through the
Northern and Central portions of the Terrific
ry, refers to this difference of temperature in
two places, and in one of them furnishes
what (to him) appears satisfactory solution
of the origin of the warm atmospheric cur
rents circulating over the country. In speak
ing of the location OF a portion of the road,
Ton page g. he says:


"This was the error that we made, and
very natural one from the MODE of reasoning
adopted by uS and many Others as fallacious
as it is paradoxical. We reasoned thus that
the Ceur d'Alene route lying to the south of
the Clark's Fork by fifty or sixty miles, and
the difference of attitude being small, that
all questions of climate were supposed to be
in favor of the more southern line: and
hence, supposing the element of climate in
both instances TO be equal, or, if there was
difference, that this difference was in favor of
the mere southern route which general
analogy would grant US, that as distauce di-
rectiOn, and connexion were all in favor of
the Ceur d Alene Pass, our location must be
via this route aud no other. But our later
winter examinations have developed this
marked and most important fact, that as you
go north in this Rocky Mountain region with
in certain limits, that the climate is milder,
the snow less deep, that horses can travel all
winter, and the general characteristics OF
winter are all less severe and that there does
exist a zone or atmospheric river of heat in
that region ] am free to vouch and can sub
stantiate by facts, and which desire to treat
upon further in my report"


On page 53, we find the following opinion
of the source of this atmospheric river:


"tThere has been no one subject so little
understood or so much misrepresented as the
climate of the northern valleys of the Rocky
Mountains and the plains extending to their
either base. am frank to admit that the
section of our road from the CGur d'Al6ne
mission to the Bitter Root ferry does inter.
pose the obstruction of snow to such an ex.
tent despair of seeing it travelled in winter
unless daily mail coach is placed upon the
line, when the snow being beaten down twice
day, would think, keep the line constant.
ly open. But all the remaining sections are
mild, with so little snow that travelling with
horses can be kept up all winter. And all
though the climate in the region first referred
to is s,severe, by going north. to the Clark
Fork, we at once enter a milder section, anC
one that offers every advantage to travel Th.
temperature of Walla- Walla, in 46o, is simi
lar to that of Washington city, in, 38o lati
tude ;sthatAo the Clark's Fork, in 48o, to tha
of ST. Joseph's, Missouri, in latitude Al tha
of theoBiuer Root Valley, in 46o, is sirnlla
that of Philadelphia, in latitude 400, will
about the same amount of snow, and Will
the exception OF few. days of intense cold
about the same average temperature Thi:
condition of facts is not accidental, bat arise:
from the truths of meteorological laws tha
are as unvarying as they are wonderful ant
useful. AS early as the winter of 1853
which spent in these mountains, my atten.
tion was called the mild open region lying
between tho Deer Lodge valley and For
Laramie, where the buffalo roamed in mil.