Mammoth Lakes, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

524
FXUS65 KREV 041931
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
1231 PM PDT Sun Oct 4 2026

.KEY MESSAGES...

* Near-record high temperatures with dry conditions through this
  afternoon, accompanied by localized wildfire smoke.

* A weak low-pressure system brings isolated light shower chances
  tonight into Monday afternoon.

* Above-normal temperatures are expected to persist through late
  week, with a cooling trend and precipitation chances arriving by
  next weekend.

&&

.DISCUSSION...

The ridging feature that is offering us the warm temperatures today
is breaking down as a trough swings through today through late
Monday. So, we will see near-record high temperatures with lower
valleys in the upper 80s to low 90s, while Sierra valleys in the mid
70s to low 80s for today, with cloud cover filtering overhead.
Current NBM probabilities show an over 80% chance for the Reno-Tahoe
International Airport to tie the October 4th record of 89 degrees.
And while this weak trough will offer clouds and showers for Monday,
we will continue to see above average temperatures through the
majority of this week. Smoke and haze from various fires around the
area may also linger, so check airnow.gov for the latest air quality
updates.

Shower chances will increase with this weak trough for Monday, with
a 15-30% chance for showers across the Sierra, with lower 10-15%
chances for the Sierra Front and the Basin and Range. While we
cannot rule out a rumble of thunder or embedded lightning in any
given shower, we are not expecting severe weather for Monday. In
fact, we have built quite a dry layer at the surface, which would
need to be sufficiently moistened to even get raindrops to reach
the ground. Wind gusts could reach 20-30 mph Monday afternoon and
evening with this system.

The upper ridge will rebound after the trough exits early Tuesday
morning, returning us to our warming trend of around 10 degrees
above average through the end of the week. Then, for the Friday in
tot he weekend time frame, a colder trough will drop into the
Pacific Northwest, bringing a stark cooling pattern with shower
chances and increased winds. Temperatures will return to seasonal
averages, with recent guidance suggesting shower chances of around
10-20% for the weekend. Of course, we will iron out details on this
as we draw nearer to the holiday weekend. HRICH

&&

.AVIATION...

* VFR conditions today with some smoke and haze lingering across the
  area, limiting slantwise visibility for some area terminals.
  Afternoon gusts 15-20 mph today.

* A weak system moves through the region late tonight into Monday
  bringing up to around 20% chances for light showers to NE CA, the
  Sierra, and the Sierra Front.

-MRC/HRICH

&&

.CLIMATE...

Near record high temperatures and near record warmest low
temperatures are forecast at both area climate sites (Reno at KRNO
and South Lake Tahoe at KTVL) for the beginning of this week.

Current record high temperatures for Reno and South Lake Tahoe:

Date       Reno NV            South Lake Tahoe CA
----     ------------         -------------------
10/4     89F (1987)                 82F (1988)
10/5     89F (1979,1980)            80F (1991)
10/6     88F (1980,1991,1996,2004)  78F (2014)
10/7     87F (1964,1980,1996,2014)  78F (1991,2014)

-------------------------------------------------------

Current record warmest low temperatures for Reno and South Lake
Tahoe:

Date       Reno NV            South Lake Tahoe CA
----     ------------               -------------------
10/4     54F (2024)                 45F (2015)
10/5     52F (1947,1999,2024)       39F (2024)
10/6     57F (2021)                 46F (2021)
10/7     52F (2021,2024)            43F (2021)


&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$