General Climatic Summary
The four seasons are actually well defined in Las
Vegas, although they differ from the traditional
view of seasonal variation. Summers display classic
desert southwest characteristics. Daily high temperatures
typically exceed 100 degrees with lows in the
70s. The summer heat is tempered somewhat by the
extremely low relative humidity. However, it is
not uncommon for humidity to increase markedly
for several weeks each summer in association with
a moist monsoonal flow from the south, typically
during July and August. Aside from increasing
the discomfort level, these moist winds also support
the development of spectacular desert thunderstorms
which are frequently associated with significant
flash flooding and/or strong downburst winds.
Winters on the whole, are mild and pleasant. Afternoon
temperatures average near 60 degrees and skies
are mostly clear. Pacific storms occasionally
produce rainfall in Las Vegas, but in general,
the Sierra Nevada Mountains of eastern California
and the Spring Mountains immediately west of the
Las Vegas Valley act as effective barriers to moisture.
Snow accumulation is rare in Las Vegas. Flurries are
observed once or twice during most winters, but
snowfall of an inch or more occurs only once every
four to five years. However, freezing temperatures
do occur with some regularity. Based on the 1971-2000
period of record, the average first occurrence
of 32 degrees in the fall is November 21; the
average last occurrence is March 7.
The spring and fall seasons are generally considered
ideal. Although rather sharp temperature changes
can occur during these months, outdoor activities
are seldom hampered.
Strong winds are arguably the most persistent and provoking
weather hazard experienced in the area. Winds
over 50 mph are infrequent but can occur with
some of the more vigorous storms. Winter and spring
wind events often generate widespread areas of
blowing dust and sand. Strong wind episodes in
the summertime are usually connected with thunderstorms,
and are thus more isolated and localized. Prevailing
wind direction is typically southwest, unless
associated with a thunderstorm outflow.
[The period used for defining temperature and moisture extremes is from January 1937 to Date.]
Reference
Gorelow, A. and Skrbac, P. 2005: Climate of Las Vegas, NV.
|
www.weather.gov 
