Montana Weather : By Season.gif)
On the previous
page, this article went over the "general
weather traits" in Montana - if there really is such a thing.
This page of the article will go over what kind of weather
you can expect in Montana - by season.
Summer Weather In Montana
Montana
has, by and large, beautiful summer weather. This is
generally pretty standard throughout the entire state,
too. Generally, from July through September (summer in
Montana), it tends to be generally dry throughout Montana,
with sunshine
the norm, with only a few days of clouds and light rain.
Yet, despite the sunshine, temperatures are generally not
too hot – unless a heat wave hits like during the summer
of 2003.
In western
Montana, look for typical summer days to run from the mid-70’s to around 90, depending where
in western Montana you are and at what elevation you find
yourself. Over in eastern Montana, highs will generally be
a tad warmer overall, with highs in the 80’s and 90’s.
During periods of heat waves, though, temperatures throughout
most of Montana can soar into the low 100’s. It is
during these times that you want to escape to the higher
elevations to avoid some of the heat. Temperatures cool off
noticeably, though, once summer flows into September – although
the days are still generally dry and sunny.
Thunderstorms
occur during the summer months, however, they aren’t especially common. Generally, more thunderstorms
occur in the eastern half of Montana than in the western
half in the summer, although the mountains can have some
fantastic lightning storms.
Moreover,
many of the thunderstorms that occur in Montana during
the summer – particularly
over the mountainous areas – are considered dry thunderstorms.
These are the most deadly of storms, since they produce huge
amounts of lightning that spawn wildfires – while not
dropping any rain. These dry thunderstorms are quite common
in Montana during the summer, and are the main cause of most
wildfires in the state.
Another
thing that needs to be remembered during the summer is
that although daytime temperatures can be quite warm,
night time temperatures can really plummet. This is especially
so in the higher elevation valleys, like the Big Hole River
valley. It is not uncommon to fall well below freezing in
places like Wisdom and West Yellowstone – even during
the height of summer when high temperatures can hit 80 degrees
or more. Yet, even outside of these cold spots, most nights
in Montana have temperatures in the 40’s or lower 50’s.
Snow in Montana during July and August happens, but not
often. Generally, if snow does happen in July or August,
it only effects the higher elevations of the taller mountains
in Montana. It is very rare to actually see snow in any of
the major Montana cities during July or August.
This
changes, though, beginning in September. Generally, the
first snow of the season coats the higher mountain elevations
in Montana in September. Occasionally the snow will also
reach the lower elevations, although the snow will not stick
around long. The nice thing about September snows is that
it coincides with the changing of the colors in the mountains – making
for absolutely beautiful sights.
Fall
Weather in Montana
Fall
weather in Montana begins usually sometime in late September
and will run into November. During this time, weather
can be highly variable – with weeks of Indian summer
weather followed by cold rain which is then in turn followed
by snow. During the fall, it becomes normal to see eastern
Montana having colder weather than western Montana, too.
The reason is because the first cold air of the season usually
arrives from Canada.
Western
Montana weather, beginning in the fall, usually begins
to start getting cloudy in October (although lately
October seems to have been as nice as September usually is).
Typically what happens in October is a mix of sunny days
followed by a week of colder temperatures under cloudy skies,
with some light rain and higher elevation snow thrown in
for good measure. November weather brings with it colder
temperatures, more precipitation and much more cloud cover
(at times, you’ll be lucky to have more than a few
sunny days in November in western Montana).
Eastern
Montana will also experience big temperature changes, really
more so than over in western Montana as it can still
occasionally get quite warm in eastern Montana in October
as warm air can occasionally get sucked up from the south.
Additionally, during October the first arctic air masses
from Canada generally arrive – typically leaving eastern
Montana under cold temperatures while the western part of
the state basks in relative warmth.
Out
in eastern Montana, snow can fall at anytime during the
fall – but it generally won’t actually start
sticking and hanging around until November in most areas.
Winter
Weather in Montana
Winter
sees some extremes in Montana weather. During the winter,
it is very common for the areas east of the Continental
Divide to be in the deep-freeze of below zero temperatures
while over in Missoula and Kalispell the temperature can
be fifty degrees warmer – and without a wind chill
to boot.
As mentioned
earlier, this occurs due to the inability of most cold
air masses to make their way over the Continental
Divide. A couple of times each winter, though, the cold air
is deep enough (high enough) to force its way through the
mountain passes along the Continental Divide – sneaking
through places like Logan Pass, Marias Pass, Rogers Pass
and other low elevation passes. When this happens, western
Montana – particularly NW Montana – can become
just as cold – if not colder – than what is found
to the east. Moreover, when this happens, the cold air has
a nasty tendency to hang around for quite a long time. This
is due to the peculiar topography of NW Montana – the
huge valleys and tall mountains frequently trap the cold
air – preventing it from being shoved out.
Western Montana during the winter receives much more snow,
generally, than areas in eastern Montana. However, all areas
of Montana can be hit hard by deep snows. Eastern Montana,
along with the occasional deep snow, also suffers from the
curse of seemingly always blowing snow.
Not
surprisingly, eastern Montana also is much windier during
the winter than is found in western Montana – just
like during the summer months. This wind, besides making
the wind chill plummet, also has a nasty tendency to blow
the snow that does fall in eastern Montana all over the place.
Huge drifts frequently form behind houses, barns, small hills
and behind anything else that the wind can’t blow away.
Snow fences along eastern Montana highways, which help to
capture snow and prevent it from blowing onto the highway,
are also a common sight.
How
much snow falls in Montana changes, often dramatically,
from year to year. The tall mountains in Montana – even
those found in the eastern part of the state – often
receive very substantial snow falls – generally ending
the year with well over 100 inches of snowpack (snowpack
= packed snow depth, not how much snow actually fell during
the year. To create a 100 inch snowpack by early April usually
requires well over 250 inches of snowfall during the course
of the winter).
By contrast, the lower valleys in western Montana tend to
avoid the deep snow that is found in the mountains. The mountains
tend to draw away the moisture of big storms, leaving lighter
snowfalls for the low elevation valleys. Generally, most
lower valley locations in western Montana tend not to receive
more than 50-70 inches of snow a year.
This changes, though, for high-elevation valleys and plateaus,
like West Yellowstone. In these locations, substantially
more snow can be expected.
Spring
Weather in Montana
Spring in Montana can be both a delight and a curse, all
at the same time. Snow can and does fall thoughout the spring
in most areas of Montana, with the snow fall probability
lessening as spring wears on. While June snowstorms can and
have happened virtually everywhere in Montana, it is a rare
for most valley locations to receive snow. Instead, the mountains
will often receive snow while the valleys receive rain.
Spring is also the rainy season in Montana. During May and
June, Montana tends to receive the most moisture of the year.
When this moisture actually happens, it goes along way towards
preventing the torrid forest fires that so often make national
news. As mentioned, most of the moisture in the valleys falls
in the form of rain during the spring time.
The
mountains, however, receive a mix of rain and snow. During
April, mountain areas tend to receive snow as the
main form of moisture. This begins to shift in May, with
the low and mid-elevation mountains receiving rain while
only the upper peaks of the mountains receive snow. By June,
most mountain peaks tend to receive rain as well – although
snow can and does happen in the mountains in June almost
yearly. Additionally, June rain in the mountains has a tendency
to be a cold rain – not a warm spring shower.
As spring
is the rainy season in Montana and because the state tends
to be dominated by NW Pacific flows, western
Montana can be very slow to warm up following winter. In
western Montana, in fact, it seems at times during May and
June that summer will never arrive – with often week
long events of clouds, cool air and light spring showers – not
something that summer dreams are made out of!
Eastern
Montana, owing to its location, tends to warm up much more
quickly in the spring than does western Montana.
While the scorching weather of July and August rarely hits
this part of the state before early-June, it does happen
for brief periods during the spring. Moreover, the rain events
in this area tend to be more of the heavy rain variety followed
by clearing skies – unlike the steady light rain/drizzle
that so often plagues western Montana for weeks on end – especially
NW Montana.
Summary
Well,
that is Montana weather in a nutshell. There is much more
to Montana weather, of course, than what this guide
lays out. Numerous sub-zones are found within both eastern
and western Montana weather zones. These sub-zones often
times have dramatic changes in weather than what is listed
here during particular times of the year. Additionally, the
mountains in Montana often create their own weather at any
time of the year. As such, while the broad, general rules
in this guide are a good rule to go by when planning a trip
to Montana, if you plan on venturing out into the mountains – always
be prepared for virtually anything. The lack of preparedness
by many a visitor has caused more than a few deceased hikers,
fisherman and other backcountry adventurers.
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