Mammoth Mountain Weather & Discussion
Almost Daily Weather for Mammoth Mountain and the Southern Eastern Sierra
Monday, July 13th, 2026 @ 8 AM
Our four corners ridge has shifted to span Montana and North Dakota. This pattern change will result in a short-lived monsoon flow today and on Tuesday, after which the area will go dry midweek.
Today’s HRRR model has instability moving into the area during the later morning and early afternoon hours with showers and possible thunderstorms at that time. Today’s action looks to be a quick mover with a possibility of dry lightning strikes.
Tuesday might turn out to be a better day, especially if we get the sun shining early in the morning. The atmosphere should be primed for T Storm action, and storms should be slower movers, resulting in some areas of isolated flash flooding.
Mid-week, the area will go dry again with a possible return to afternoon and evening t-storms in the forecast by next weekend. This change in the pattern will allow the area to cool a bit to average highs for July.
Steve Taylor, the Snowman out…
Below is the most current HRRR model as of this post. This GIF below goes out for 48 hours and shows you where it’s forecasting rain and thunderstorms.
Detailed Local Weather Forecasts:
Main Lodge / Mammoth Lakes Basin:
Mammoth Lakes: Today – A 50 percent chance of showers and thunderstorms after 11 am. Increasing clouds, with a high near 73. Calm wind becoming south around 5 mph.
Mammoth Long Range Outlook Data
Here is the ECM Ensemble Model out to day 16.
Here is the QPF output from the ECMWF.
Daily Afternoon Summer Zypher winds will continue for the foreseeable future.
Temperature Anomalies GiF
45 Day Precipitation Anomaly
❓ 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.