Mammoth Mountain Weather
Forecast & Discussion
Tuesday, October 28th, 2025 @ 11 AM – Gorgeous fall days continue as ridging and higher heights have taken over the area for the foreseeable future, a great week to get out and enjoy the area before winter sets in.
For the next 7 days, expect dry & warmer weather, with little to no snowmaking possible up at the Main Lodge.
On days 8 and 9, a small shortwave appears to move through the area, bringing a possible dusting of snow, breezy conditions, and some cooling. There could be a couple of small windows for snowmaking, but the short wave is coming off the Pacific with no cold polar air.
Looking out in the Ultra Fantasy Long Range Outlook, higher heights are expected to be the leading player through mid-November, and then by week 3, we see heights lowering with possible snow showers and colder nighttime weather for snowmaking during the time frame.
After the 21st of November, according to the longest weather trend models, the 7-day precipitation anomaly outlooks each week show green extending into mid-December. Of course, models that far out are not for forecasting; they show us how all the models are trending.
Snowmaking Update – Waiting on the Cold: Looking ahead, there’s little opportunity for snowmaking over the next 7 days.
There you have it, today’s Mammoth Weather Story. The good news is that we can see some hope on the horizon for a possible change in the weather. Enjoy the weather while we wait.
Steve Taylor – the Mammoth Snowman
PS: Check out the ever-building weather link page.
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.