Mammoth Mountain Weather & Discussion
Almost Daily Weather for Mammoth Mountain and the Southern Eastern Sierra
May 13th, 2026 @ 8 AM – Looks like a great day to get out and play with clear skies this moring. Expect come build ups today with a few very islolated showers mainly south of the Mammoth Lakes region.
Mammoth Weather Forecast: Midday temperatures at Main Lodge will be in the mid-60s today, with upper-60s expected on Thursday and Friday. Overnight lows will be in the mid-40s by Wednesday night, then lower a bit each night. There is a chance of a light freeze-up on Top this weekend.
Winds will be light and variable, out of the southwest 5 to 10 mph in the afternoon. Winds could gust as high as 20 mph with gusts on Friday in the 30 – 40 mph range.
Mammoth Weather Discussion
A weak low-pressure system is moving into the Oregon-Northern California border area today. As it moves east, there will be a few buildups along the Sierra Crest, with isolated showers possible from Mammoth Mountain down into the Southern Sierra.
Thursday into Friday, higher heights will prevail with lighter winds and a bit of warming. By the weekend, a cooldown returns, with an inside slider becoming the main player. Expect cooler temperatures, increased northeast winds, and the possibility of a light freeze on Saturday and Sunday night. The slider may continue to affect the region into early next week.
Then ridging takes over again by midweek. As we approach Memorial Day Weekend, a cutoff low looks to develop off the Southern California coastline. As we all know, these little cutoff lows can be very difficult to forecast this far out.
Based on the current trend, there appears to be at least a decent chance for afternoon buildups and scattered showers over the Holiday Weekend, with snow showers possible over the higher terrain. We’ll be keeping a close eye on how things evolve over the next several days.
Stay tuned. I plan to update the weather page 2-3 times per week over the next few months, as time allows.
Snowman
Enso – El Niño Watch 2026-2027
4-24-26 – There continues to be a lot of growing interest in the long-range pattern as we move deeper into spring, and for good reason.
The Pacific Ocean is showing increasing signs that an El Niño may develop during late spring and summer, which could have important implications for California weather later this year and into next winter.
At this time, conditions are still officially classified as ENSO-neutral, meaning neither El Niño nor La Niña is fully established at this time.
However, that neutral label can be misleading. Under the surface, warm water has been building in the equatorial Pacific for several months now, and many major climate models continue to warm the basin through summer and fall.
Current NOAA Outlook
NOAA guidance currently favors:
- El Niño development during the May through July period
- Increasing odds that the event continues through the second half of 2026
- A growing chance that this becomes an important winter story later this year
What The Models Are Showing
The ECMWF seasonal model is showing a growing, very warm tongue of water across the central and eastern Pacific through summer and fall.
The most aggressive long-range guidance, the CFS (not my favorite model), continues to advertise a healthy warming event by late summer into fall with water temps in Super El Niño territory.
A word of caution, it’s only April, and I have seen these strong El Niño forecasts go bust in the past, so let’s not buy into any of the hype you will be hearing the next few months.
>> Long-range model swings are common this time of year, and no winter snowfall outcome should be promised off April charts.
East-Based vs. Modoki Matters Big Time
When I hear El Niño Modoki and think back to the El Niño bust years that brought well-below-normal snowfall to Mammoth Mountain, like the 2016 event. When I hear about a strong East-based El Niño, I start imagining a deep snowpack that built up over the season.
East-Based El Niño
In this setup:
- Warmest water shifts farther east
- Stronger forcing near South America/eastern Pacific
- Better chance of energizing the subtropical jet
- Better odds for wetter California patterns
Modoki / West-Based El Niño
In this West-based El Niño setup:
- Warmest anomalies stay centered farther west
- Tropical forcing shifts toward the central Pacific
- Jet stream can create the split flow blues – (ex. 1987-92 winters)
- California signal becomes less reliable
That is why hearing “El Niño is coming” means very little without knowing what kind is developing.
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What We Want To See This Summer
If this event is going to become meaningful for California and Mammoth, I want to see:
- Continued warming through summer
- Warm anomalies migrating east
- Niño 1+2 and Niño 3 regions strengthening
- More westerly wind bursts across the tropical Pacific
- Trade winds weakening and staying weaker
- Atmospheric coupling locking in by late summer
Snowman
❓ 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.