Mammoth Mountain Weather Forecast
Including Mammoth Lakes & Bishop, California
Monday, September 16th at 3 PM Currently, Mammoth Mountain and the Southern Eastern Sierra are under cloudy to partly cloudy skies. Light snowfall has been recorded in the Rock Creek Canyon area, over the Sierra Crest, and in the White Mountains above Bishop. So far, I have seen nothing fall up at the ski area.
I checked the area weather stations this afternoon. Up top, the temperature is 27 degrees with an S wind at 26 MPH, gusting to 34 MPH. Down at the Main Lodge / 8900 elevation level, the temperature is 39 degrees with a SW wind at 5 MPH, gusting to 20 MPH at times.
The temperature is 45 degrees in Mammoth Lakes, and the Mammoth Airport is 50 degrees, with 48 degrees in Crowley Lake and 64 in Bishop.
Weather Forecast for Your Adventure
Tuesday: Expect clear skies to start the day, and then increasing clouds will be possible during the afternoon. By late Tuesday night, there could be light rain and snow showers over the higher terrain, with snow levels at 10,000 to 11,000 in elevation.
Wednesday through Thursday: There will be a 60-80% chance of light rain & snow with a few isolated thunderstorms.
Snow levels will be around the 9200 to 10,200-foot level. Snowfall accumulations will be a dusting of slop to possibly an inch above the 10,000-foot level.
Some heavier showers could pull the snow level down to the Main Lodge early Thursday morning. So don’t be surprised if you see snowflakes on the main lodge webcam before the rain returns.
A slight shift in this system could bring cooler temperatures. If that happens, snow levels will decrease slightly, and accumulations will increase.
Basic Weather Details: For the Main Lodge / 8900 Feet, Midday temperatures at the 8900-foot level will be in the mid-50s on Tuesday, mid-40s on Wednesday, and mid-30s by Thursday. Overnight lows will be in the upper 30s to mid-40s.
The Wind forecast calls for a SW Wind at 5-10 MPH, with gusts up to 25-35+ MPH from Main Lodge up to the top of the Mountain.
Midday temperatures in Mammoth Lakes midday temperatures at the 8900-foot level will be in the upper 50s on Tuesday, low 50s on Wednesday, and mid-40s by Thursday. Overnight lows will be in the upper 30s to lower 40s.
For Bishop to Mill Pond, mid-day highs will be in the upper 60s to lower 70s, with overnight lows in the low to mid-40s.
Mammoth Mountain & Eastern Sierra Weather Discussion & Outlook
The first of two September low-pressure systems is working its way through the area this afternoon. Snow showers have been reported from the White Mountains to Bishop Creek Canyon and up in Rock Creek Canyon. So far, Mammoth has missed out on a dusting of snow today.
The next upstream system looks to be a better precipitation producer. The storm will start on Wednesday and last into Thursday. As the system comes through, the QPF for Mammoth is still a bit weak, with a possible water content of .25 to .50.
There are some wetter solutions for system 2, but it’s hard to really buy into them yet. When I post again on Wednesday, there should be some better data to look at regarding how much rain and snow the area might get or not get. The main punch from the second system, as of now, looks to be Wednesday night into Thursday afternoon/evening.
The Weekend Outlook: The Southern Eastern Sierra will clear out with warming temperatures and decreasing winds. Mammoth Lakes will be in the mid-60s during the middays, with Bishop in the low to mid-80s. It sounds like a perfect weekend for a nice adventure.
Longer Range Fantasy Outlook 10-45 Days: In the more extended range, fantasy outlook period for the last week of September. The ECM ENS model has higher heights and dry conditions for what would be considered Indian Summer Weather. (That is assuming one of next week’s two systems does bring a dusting to the high country.)
When comparing the GEFS model to the ECM, you see slightly cooler temperatures overall and lower heights in the area. If the area does warm up again, as I expect it to, don’t expect temperatures to be hot like in the Summer months.
Looking way out into the Fantasy Forecast period for October’s weather trends, the ensemble models still show warmer and dryer days overall.
The one thing that could change is that a typhoon would merge with the westerlies and send some moisture our way. That weather pattern is more likely for Mammoth from mid-October to early November.
Steve Taylor – the Mammoth Snowman
The next full Mammoth Weather Forecast Update will be Wednesday by 5 PM.
Mammoth Weather Forecast Data from Weather Bell
ECM & GEFS Ensemble Models 500
15-Day ECM 500mb Anomaly GIF: Below is the entire 15-day run of the ECMWF ensemble model. I use this model to tell the Mammoth Weather Story you just read above. Compared to the other models, this solution has been effective more often than others over the years.
16-Day GEFS Ensemble 500mb Anomaly GIF: Below is the second most trusted ensemble model that we use that goes out to day 16. Model relaibily beyond day 7 can be very suspect expecialy during the transition seasons of Spring and Fall.
ECMWF Ensemble Jet Stream Gif
This is the Eastern Pacific View of the ECMWF ENSEMBLE Run of the Jet Stream.
Temperature Forecast
Temperature Anomaly GIF: Over the next week, expect a slow cool down, as shown below, with the blues moving over California. The cooler weather looks to be in the area for the next 10-14 days before there is a bit of a warm-up again. You can kiss the heat of Summer goodbye this week in the Southern Eastern Sierra.
*Temperature anomaly means a departure from a reference value or long-term average. A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.
The Wind Forecast
QPF Forecast
Snowfall Forecast
Precipitable Water Anomaly
45-Day Long Range Fantasy Outlook
This is the long-range ultra fantasy 45-day model run. These longer-range ensembles are good for examining long-range trends in the overall weather pattern. They should never be used or considered a forecast.
46-Day Fantasy Snowfall Outlook
First Look at Snowfall Season 2024-25
9-5-2024 – When looking ahead to the next snowfall season, predicting what might happen is difficult at this time of year. If a weak La Nina does form (66%), there is a good chance we will have a drier-than-average snowfall season.
However, several very big winters have come from weak La Ninas over the last 25 years. (See the La Nina Winter chart down the page.) Everyone must also remember that many other factors are at play than just warm or cooler water along the Pacific equator.
For now, Ted (Powder Forecast) and I are not forecasting what the winter might be like. We will better understand how this may play out in late October / early November. As we have all seen in the past, patterns can quickly flip and change in late December and January.
La Nina seasons are like El Nino and can bring drought, moderate winters, or large ones. Many factors are at play, and the situation can change as the winter season starts to ramp up in mid-to-late December.
Let’s keep the positive vibes that Mammoth Mountain gets a perfect winter, with moderate amounts of powder snow mixed in with some dry periods and endless wind-buff days.
Steve Taylor – The Mammoth Snowman
PS The new runs of the ECMWF Seasonal come out for forecasters on the 5th of each month.
La Nina Years Snowfall Totals for Mammoth Mountain
Weak La Nina
1971-72 Snowfall Total = 268 with 139 in December
1984-85 Snowfall Total = 236
2000-01 Snowfall Total = 393 with 124 in February
2005-06 Snowfall Total = 578 with 4 100+ inch snowfall months
2008-09 Snowfall Total = 470 with 2 100+ inch snowfall months
2016-17 Snowfall Total = 617 with 245 January 163 February
2017-18 Snowfall Total = 262 with 142 in March
Moderate La Nina
1970-71 Snowfall Total = 255
1995-96 Snowfall Total = 321
2011-12 Snowfall Total = 263
2020-21 Snowfall Total = 244.5
2021-22 Snowfall Total = 260
Strong La Nina
1973-74 Snowfall Total = 306
1975-76 Snowfall Total = 197
1988-89 Snowfall Total = 251
1998-99 Snowfall Total = 323
1999-00 Snowfall Total = 382
2007-08 Snowfall Total = 333
2010-11 Snowfall Total = 668
2022-2023 Snowfall Total = 717 – Largest Winter Recorded over the last 100 years
ENSO Watch
Last Update from DWP Precipitation for Mammoth Pass & the Eastern Sierra
Most Recent Posts
*Mammoth Mountain and Eastern Sierra Weather is updated Sunday, Tuesday & Thursday by local Steve Taylor, the Mammoth Snowman. The goal is to provide detailed weather forecasts presented in an easy-to-read format. This isn’t a Hype, one-and-done model-run website. It’s just the basic facts from how I see it after 40 years of being involved in local weather and recreation. And yes, I use Weather Bell for my forecasting data.
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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 MammothSnowman.com in 2004 with Video and photo Blog reports. (There was No YouTube back then.) Facebook was added to the fold in 2008, and the Facebook Group was added in 2016.
Reports, videos, and photos from the website have been featured on local TV Stations here in Mammoth and Bishop, as well as KTLA, AP, Fox, ABC, CBS, and NBC News.
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