Mammoth Mountain Weather
Forecast & Discussion
November 2nd, 2025, at 9 AM – Look for clear skies through Tuesday, with a cooling trend starting on Monday and breezy conditions in the high country. Winds will be light today, then SW at 5-10 mph with gusts up to 25+ mph on Monday and Tuesday.
Main Lodge tempretures will be in the lower 50s today, mid-40s on Monday and Tuesday, then mid-30s on Wednesday with a chance of rain or snow showers with the snow level 8,500 to 9,000 feet.
Look for a dusting at Main, and at best, about an inch of accumulation over the higher elevations with snow ratios at 3 to 1.
Snowmaking: Marginal Snowmaking conditions tonight into Wednesday night, and then it will be too warm to blow until the following week. Looking farther out, I see decent snowmaking conditions by mid-month and onward.
Mammoth Weather Discussion
Short term – One last day of warm and calm conditions in the area as a ridge of high presure is set up just to our east with well above average heights in the area. On Monday, the area of high presure will move further to the east as a low-pressure system approaches from the west. This will lead to a cool down on Monday onward, with breezy conditions.
Mid-Week – The low-pressure system approaching from the west is deflected northward as the ridge to our east is too strong, sitting over Colorado.
Mammoth Mountain is in the weak QPF zone with .01 to .03 of precipitation expected. Snow ratios are in the 3:1 range, so expect a dusting to an inch at best. If the system drops southward a bit, Mammoth could see 2-3 inches of glop above the Main Lodge.
Late next Week into the weekend – Ridging sets up to our SW, keeping any storminess well to our north. This pattern will offer no help to the snowmaking crew as they will be on hold until the ridge moves out.
Opening Week Fantasy Land Time Frame – For opening week, the weather trend appears to be moving into a much more favorable pattern for both nighttime snowmaking and accumulating snowfall.
The ECMWF ENS and the GEFS each feature a couple of weather systems; the first system will break down as it moves into the ridge, opening the door for the second system to move through without the strong ridge in place.
Since this is the fantasy time period, you can expect to see some wild to not-so-wild outcomes on the models over the next 10 days, leading up to the possible change to wetter and cooler weather. If you’re a weather model, riders don’t buy into significant changes you see every 6 hours.
Ultra Fantasy Land – Week 3 – The ECMWF Weeklies have the Eastern Sierra under below-average heights, with below-average tempretures and some snowfall added in. That far out, we are just looking at trends in what may come weather-wise, so we have no idea what the snowfall would amount to.
Snowmaking Forecast and Outlook: Marginal Snowmaking conditions tonight into Wednesday night, and then it will be too warm to blow until the following week. As you can see below
Looking farther out, I see decent snowmaking conditions by mid-month into Thanksgiving week. 
That is your Sunday deep dive into the start of the new season. Keep the faith in a big change in about a week to 10 days. Can’t wait to see you all on the slopes again.
Snowman
NOAA 6-10 Day & 8-14 Day Outlooks
October Seasonal Model Update – Looking Toward Winter 2025–26
10-5-25 @ 5 PM – The latest ECMWF seasonal update just dropped, and we’ve dug through every chart and model trend to see what this winter might bring to Mammoth Mountain.
The signal this year? A weak La Niña that fades fast — a setup that often means a slow start, followed by a better shot at storms once the pattern relaxes.
That’s a familiar pattern in the Eastern Sierra. Early winter can run lean while the Pacific jet stays aimed a bit north, but once it sags south, things can change in a hurry.
The key question this year isn’t whether storms will come — they will — but when the pattern opens the door and how cold those early ARs run.
Looking for years to match this Fall is tough. Here are the ones that are the closest: 2000-01 (393), 2005-06 (579), 2016-17 (618), and 2017-18 (262).
I will have more information on this in a couple of days, once I have concluded my research on past patterns.
Snowman – Next Model Update on 11/5/25
❓ Top Mammoth Weather Questions (from the Snowman)
When does Mammoth usually get its first snowfall?
Light snow can fall in late September, but consistent snowfall usually begins in late October or early November. Opening Day typically lands between November 10 and Thanksgiving, depending on storm activity and snowmaking.
How does the ENSO pattern affect Mammoth’s late fall and winter weather?
ENSO (El Niño/La Niña) plays a big role in Sierra storm patterns. El Niño winters often bring warmer, wetter storms. La Niña typically favors colder, backloaded seasons with more snow from February through April. Neutral years are the wildcards with high variability.
What is 500mb height and why does it matter?
500mb height maps show atmospheric pressure around 18,000 feet — a critical layer for tracking storm tracks, ridging, and jet stream placement. Watching 500mb patterns helps forecast Mammoth’s incoming storms and long-range trends.
What are the PNA and PDO, and how do they affect Mammoth weather?
The PNA (Pacific-North American Pattern) influences western U.S. ridging and troughing. A negative PNA favors cold, stormy setups. The PDO (Pacific Decadal Oscillation) affects sea surface temperatures in the North Pacific — a negative PDO often aligns with enhanced storm delivery into California during winter.
👉 Want more answers? Check out the full Mammoth Weather FAQ – 50 Expert Answers to learn more about storms, snow, winds, and long-range patterns from a trusted local source.
Author Bio: Steve Taylor, The Mammoth Snowman. Over the last 40+ years, Steve has spent countless hours studying and learning about Mammoth Mountain Weather and Snow Conditions.
Dr. George, Don Marcelin, Howard Sheckter, and Ted Schlaepfer were his weather mentors at that time. Steve used to hang out with Howard in the Weather War room in the early ’90s, getting first-hand knowledge of Mammoth Weather from the (The Dweeb) himself.
Steve has spent countless hours reading, studying, and watching weather discussions from the NWS and multiple Private Weather Forecasters. He is a long-time member of WeatherBell, Weather West, and AccuWeather Pro. Disclaimer: Steve is a hobbyist forecaster with over 35 years of experience reporting recreational weather and travel reports for the Mammoth Lakes area.