Mammoth Mountain Weather Forecast & Discussion

October 20th, 2023 @ Noon – Good Afternoon; you will find mostly clear skies in the area today with just a few clouds around and a bit of haze in the lower elevations.

Currently, out on Mammoth Mountain at the 9600-foot level / MC Coy Station, the temperature is 53 with a wet blub of 42 degrees. Winds are out of the NNW at 5 to 12 MPH. Up at the Summit, the temperature is 45, with winds out of the S at 24 to 31 MPH.

Down in Mammoth Lakes, there is a temperature of 65, with a 69 at the Mammoth Airport. In the town of Crowley Lake, the temperature is 69, and down in Bishop, there is a temperature of 77. No winds to report in the lower elevations at this time. 

Into next Tuesday, here is what to expect weather-wise out on Mammoth Mountain and around the Eastern Sierra. Look for clear skies and just above-average temperatures the next couple of days as a ridge of high pressure exits the area.

Temperatures will start to drop today from Thursday’s peak and will continue to drop into Monday by about 20 degrees before starting to come up again on Tuesday.

The ridge that is moving out today will be replaced by a weak low-pressure system that will move down the Sierra and into the deserts of Southern California early Sunday into Monday.

The low is looking pretty much moisture-starved, however, some models still have a bit of moisture over Mammoth Mountain. There could be a slight dusting of snow with some snowflakes Monday Morning.

By next Tuesday, higher heights will be up in the area bringing in warming temperatures.

Snowfall Forecast for Mammoth Mountain Ski Area - Mammoth Weather Image
Snowfall Forecast for Mammoth Mountain Ski Area

5 Day Weather Forecast for Mammoth Mountain and Mammoth Lakes: Skies are expected to remain mostly clear with just a few high clouds at times from the Mountain down into the Bishop area right through Sunday.

There will be a 20-30% chance for light snow showers late Sunday evening into the early hours of Monday morning, with the snow level above 8500-9000 feet. The QPF from this system for Mammoth Mountain is .00 to .10, so a slight dusting of snow is not out of the question.

Mid-day temperatures out on Mammoth Mountain @ the 9000-foot level will be in the upper 50s to low 60s Today and Saturday, with temperatures coming down into the upper 40s to lower 50s on Sunday with lower to mid-40s on Monday.

Night-time lows will be in the low to mid-40s into Sunday morning. With lows down near freezing on Monday and Tuesday mornings.

The wet blub looks to be too warm to make snow through Sunday. There does look to be a small window to blow snow early Monday and Tuesday if they want to test the system. No idea if they will or not.

The Wind Forecast for the upper elevations SW winds @ 10 -15 Mph with gusts in the 20-35+ MPH range over the highest elevations and ridge tops into Saturday. Winds will pick up on Sunday as the low makes its way into the area.

For Mammoth Lakes, today and Saturday, mid-day temperatures will be in the low to mid-60s with mid-50s on Sunday and then down into the upper 40s on Monday. Night-time lows will be in the upper 30s to lower 40s into Saturday morning and then near freezing Sunday night and Monday Night.

Down at the 4100-foot level in Bishop, mid-day temperatures will be in the low to mid-80s today into Saturday, and then into the 70s Sunday and 60s Monday and back to the 70s on Tuesday. Night-time lows will be in the upper 40s through the weekend and will fall into the upper 30s by Monday morning.

Snowman out...

For my Full Weather Discussions and Longer Range Outlook Data, scroll down to the next section. Make sure to sign up for my Newsletter first…

Days 1-5 Mammoth Weather Discussion & Images

October 18th @ 8 AM – A very strong ridge for mid-October will move through the area for the next 48 hours. Temperatures will be well above average into Friday and then fall 15 to 20 degrees by Sunday as the weak inside slider drops just to the east of the Sierra Crest. The path of the low is a dry one, and QPF for this system is weak at under .10. There could be a bit of a dusting of snow, but that may be out of the cards this one is looking drier each run.

ECMWF out to mid day on Tuesday - Mammoth Weather Image
ECMWF out to mid-day on Tuesday


5-Day Temperature Forecast

5-Day Snowfall Forecast

Snowfall Forecast for Mammoth Mountain Ski Area - Mammoth Weather Image

5-Day Wind Forecast

5-Day Wind Forecast - Mammoth Weather Image

5-Day Wetblub for Snowmaking Forecast5-Day Wetblub for Snowmaking Forecast - Mammoth Weather Image


** Weather Disclaimer: The Fantasy and Ultra Fantasy Outlooks are “Outlooks, Not Forecasts.”  Some years, the wet patterns that appear in these longer range outlooks pan out; other times, the changes are always out in the fantasy period and never make it to the short-term forecast period. When all the ensemble models have agreement on wet or dry patterns, more often than not, they do seem to pan out more often then not.

6-16 Day Fantasy Weather Outlook

October 18th @ 8 AM – The ensemble models below are in disagreement on how the pattern goes on days 6 and 7. The GEFS has a second inside slider, while the ECMWF has some higher heights.

Unfortunately, they both agree on more ridging by the end of October and into Day 16 at this time. In my last update, we saw some long wave troughing and more snow for this time frame, but that pattern appears to be gone for now.

That is typical in weather modeling at this time of year, with a decent pattern showing up for a few days and then it’s gone. There is a lot of uncertainty moving forward with the weather pattern for early to mid-November at this time.

Day 6-16 - ECMWF ENS 500 Height Anomaly
Day 6-16 - GEFS ENS 500 Height Anomaly



NOAA 6-10 Day Temperature Outlook for Mammoth Mountain and Mammoth Lakes
NOAA 6-10 Day Temperature Outlook for Mammoth Mountain and Mammoth Lakes
NOAA 6-10 Day Precipitation Outlook for Mammoth Mountain and Mammoth Lakes
NOAA 6-10 Day Precipitation Outlook for Mammoth Mountain and Mammoth Lakes

Day 16-45 – Ultra Fantasy Weather Outlook

October 18th, 2023 @ 9 AM – As of now, the longer-range outlook that I trust myself with for November has the area with average temperatures and below-average snowfall. That follows the EC ensemble thinking.

That said, the CFS Daily Mean is much wetter for November, so snowfall could go either way. Hopefully, the CFS is on to something the EU is not picking up. In a couple of weeks, there should be more clarity on how the season’s first month will pan out weather-wise.

Day 16 – 45 – ECMWF Extended Ensemble Mean

45 Snowfall from the ECMWF Ext. Ensemble Mean

Temperature Anomaly – ECMWF Ext. Ensemble Mean

Precipitation Anomaly November 2023- ECMWF Extended Ensemble Mean

Total Precipitation November 2023 – CFS Daily Model

ENSO – El Nino / La Nine Outlook – September 26th, 2023

El Niño Update: The current El Nino is in the strong category. How the event affects Mammoth Mountain and the Eastern Sierra this winter is uncertain. There are a lot of variables with this particular El Nino event that have not been seen during other strong events. Take a look at the video below for more information.

There are not a lot of strong El Ninos to look back at, so it’s hard to trust any of the long-range data right now. Past El Niño winters have been slow to start, so don’t be surprised if the Eastern Sierra sees below-average rain and snowfall this Fall. 

The video below is new from Mike Discussing the most current El Nino Data. All the images in this section have been updated, with what’s the most recent on there as of 9-26-23.

> To note, El Niño winters can be slow to start, so don’t be surprised if the Eastern Sierra sees below-average rain and snowfall this Fall.

SSTA Mammoth Weather Forecast
SSTA Mammoth Weather Forecast

Current Weather and Information Posts

Author – Steve Taylor – The 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 reports. (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 and Bishop, along with KTLA, AP, Fox, ABC, CBS, and NBC News.

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