Mammoth Mountain & Eastern Sierra Weather Forecast

Mammoth Mountain & Eastern Sierra Weather Forecast

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Mammoth Lakes and Eastern Sierra Weather for Sunday, September 5th, 2021 @ 12:54 PM

Good Sunday afternoon, we have clear skies with great air quality here in the Eastern Sierra from Mammoth Lakes down to Bishop. Nights are getting nice and cool, with Summer still hanging on during the afternoon and evening hours.

Weather Synopsis… Mammoth Lakes and the Eastern Sierra is under the influence of a strong ridge of high pressure at this time. The ridge is looking to hang out in our area a bit longer than expected so you will continue to see above normal highs into Wednesday.

At that point the ridge will start to move slowly east and that will open the door to a weak late summer monsoonal  pattern with a chance of T Storms by next Thursday into the following Saturday.

Weather models the last few days looked a bit wet for late next week but have now backed off over the last 12-24 hours. Pretty much to be expected during September.

If we do get T Storms next week let’s pray they moisten up a bit, last thing we want to see right now if more fires and excessive smoke.

I will be watching how this pattern sets up daily this week and will update on Monday if there are any big changes. If not the next update will be Tuesday afternoon.

Also to note: The New ECMWF Long range charts got released to me this morning, I have posted the outlooks for the October – January time frame down the page. They sure look better then what a lot of people are expecting to see.

7 Day 500 h Pa Hieght Anomoly

Smoke and Haze Update: The smoke moved back in on Friday and cleared out by the end of the morning on Saturday. Today we have some light haze but air quality is good. Looking at the smoke forecast for the next couple days. Right now the HRRR smoke images below do show us in the ok to good range to be outside working or exercising over the next 48 hours. (The HRRR smoke forecast can be really good but if any new fires happen or there are major flare-ups on the current fires, that forecast could change.)

Here is the link you can use to monitor the air quality in the Eastern Sierra. When the pointer is in the green or yellow range you’re good to go out and play. When the pointer hits orange and red I would avoid being outside for extended periods of time.

Also to note, only the N95 masks work to help prevent the haze and smoke particles from entering your lungs and bloodstream. The blue masks everyone is wearing are worthless against wildfire particles.


Temperatures: Highs for Mammoth Lakes will be in the low 80s into mid weeks with Bishop in the upper 90s during the afternoon and evening hours.

Night-time lows will be in the mid to upper 40s for the high country and into the upper 50s to low 60s for Bishop and Round Valley.

Winds: Expect southwest winds in the 5-10 MPH range in the lower elevations with upper elevations seeing gusts in the 10-20+ MPH range at times.

Here are the links to the local NWS Forecasts for Main Lodge & the Mammoth Lakes Basin, Mammoth Lakes, June Lake, Crowley Lake, and Bishop.

Extended Outlook: Looking out towards the early Fall season we can expect to start to see insider sliders show up by late September into early October. Many a year there will also be the first dusting of snow later in the month of September.

I am watching daily and will post when we have something to talk about. I do promises not to jump on the hype train here with false expectations.

The next long range charts for the ECMWF should be out in the next 24-48 hours and I will post them up as soon as I have access.

For the upcoming Winter, more then half of the extended models have us in a neutral ENSO state, with some showing a weak La Nina. As of now, I expect the chances of an average snowfall winter are much greater than a 3rd year of exponential drought.

Current Model Images Updated on Sunday 9-5-2021

HRRR Temperature Forecast

HRRR Precipitation Forecast

HRRR Current Dew Point

HRRR Current Humidity Levels

Precipitable Water

ECMWF EPS Accumulated Precipitation



ECMWF EPS Ensemble going out 10 days / 240 hour

360 Hour & 45 Day Snowfall Outlook

Long Range Outlooks from the ECMWF – Next Update on these images is 9-5-21

Mammoth Mountain and Eastern Sierra Weather Posts

Who Are We?

Steve Taylor – Mammoth Snowman Over the last 30+ years, Snowman has spent countless hours studying and learning about Mammoth Mountain Weather and Snow Conditions first hand. He has been skiing around the hill with marked ski poles since March of 1991 so he can measure the fresh snowfall amounts out on the hill. 

Snowman started blogging this information back in 1990 on the old Mammoth BBS system, then the RSN Forums and then on to in 2004 with Video & Photo Blog report. (No YouTube back then). Facebook got added to the fold back in 2008 and then the Facebook Group in 2016. 

Reports, videos, and photos from the website have been featured on both local TV Stations here in Mammoth, along with AP, Fox, ABC, CBS, and NBC News.

Ted Schlaepfer – Mammoth WeatherGuy – The Powder Forecast – Posted Tuesday and Fridays at 5 PM November into Mid May. These forecasts are now responsible for many people getting multiple powder days on Mammoth Mountain over the years.  

Ted’s Bio: Ted has been a full-time Meteorologist (CCM) for the past 25+ years. He has always been fascinated with the weather,” skiing was just a natural extension of my love for snow and rain. I started skiing at age 5,  first discovered Mammoth in 1979 as a youth, and have been a regular visitor since the late ’80s.”.

Here is the link to The WeatherGuys Powder Forecast Page. 

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