Mammoth Lakes (Mammoth Mountain) weather in December
December in Mammoth Lakes: cold, rainy, with clean air — an excellent time to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#4 of 12 months in Mammoth Lakes · #404 of 1413 destinations to visit in December · comfort 82/100 (tier A)
- Days
- 6°C
- Nights
- -9°C
- Wet days
- 8
- Sun
- 7.6 h
- Humidity
- 65%
- Daylight
- 10 h

Traveller notes on Mammoth Lakes in December
Other months in Mammoth Lakes
Mammoth Lakes-forum threads on an October visit describe peak fall color as genuinely running mid-September through early October, posters warning color at higher elevations has typically passed by the twentieth. Regulars call June Lake Loop, Lundy Canyon and Rock Creek Canyon real standard viewing spots, several posters naming the Tom's Place turnoff as the way into Rock Creek's aspens. Posters call Convict Lake's aspen grove a real highlight, several regulars naming its roughly three-mile loop as an easy way to see color without a long hike. Regulars call timing genuinely shifting year to year with weather, several threads recommending checking weekly updates at the Welcome Center before planning around peak color. Posters recommend lower-elevation spots once higher color has passed, several regulars calling this standard given how the show moves downhill as October progresses. The record: 17.3C days, -1.5C nights, 21.3mm across nearly 3 days and 48 percent humidity.
Mammoth Lakes-forum threads on a late-September visit describe afternoon highs as typically running around the mid-seventies Fahrenheit, posters calling nights considerably chillier, dropping into the mid-forties. Regulars call this genuinely one of the better stretches for hiking, biking, boating and even a last swim, the lakes about as warm as they get all year by this point. Posters recommend Hot Creek, the Earthquake Fault and the Twin Lakes waterfall as easy local drives, June Lake Loop, Mono Lake and Bodie all reasonable if venturing further. Regulars call heading into the high country, Rock Creek to the south or Tuolumne Meadows to the north, a real chance at early fall color. Posters describe local events like an art festival over Labor Day weekend as worth timing a visit around. Regulars recommend real layers for the evening chill despite the pleasant daytime warmth. The record: 22.3C days feeling like 20C, 3.2C nights, 12.5mm across nearly 4 days and 47 percent humidity.
Mammoth Lakes-forum threads on April skiing are consistently enthusiastic, posters calling this among the strongest months of the season thanks to a deep base built from heavy earlier-season storms. Regulars describe spring snow here as genuinely excellent once it softens, smooth corduroy in the morning turning forgiving rather than icy by afternoon. Posters call the mountain noticeably less crowded than winter break, some describing it as nearly empty by mid-to-late April. Regulars are direct year-to-year variability is real, some Aprils bringing fresh storms and a foot or two of new snow, others closer to a bare, sunny stretch. Posters recommend checking current conditions before committing to a specific week. Regulars call the full mountain typically open through the third weekend of April most years. The record: 10.9C days feeling like 9C, -3.2C nights, a notably high 21.6cm of fresh accumulation and 68 percent humidity.
Mammoth Lakes-forum threads comparing seasons call July genuine peak summer, wildflowers out at the high elevations and conditions noticeably milder for hiking than the intense heat of late August. Posters name Devils Postpile, Rainbow Falls and Red's Meadow as standout July destinations, along with the Mono Lake and June Lake Loop area just north for swimming, hiking and horseback riding. Convict Lake, a short drive south, is repeatedly recommended as an easy add-on for anyone with a spare afternoon. Regulars call the days noticeably longer and the evenings still comfortable compared to how quickly things cool once late August arrives. Layers for a genuinely large day-to-night swing at this elevation are standing advice regardless of how warm the afternoon runs. The record: 26.8C days feeling like 25C, 7.3C nights, a low 42 percent humidity and 14.5 hours of daylight.
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Mammoth Lakes climate normals — December
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Mammoth Lakes in December
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsMammoth ski season, Christmas to New Year ski peak, Winter / Christmas break in United States(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Mammoth Lakes's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherMammoth Lakes's weather peaks January–March, best around February.
Best weatherFair weatherToughest weather
What's on in Mammoth Lakes in December
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
Mammoth ski season
5 Nov – 31 May · usuallyCrowdedMammoth holds snow longer than anywhere else in California and regularly spins lifts into late May, sometimes past it. The town lives on the season, and weekend traffic on US-395 out of Los Angeles is the price of it. Source ↗
- Holiday
Christmas to New Year ski peak
20 Dec – 3 Jan · usuallyChristmas & New YearCrowdedBook earlyThe week from Christmas to New Year is the busiest of the ski season: lodging and lift-ticket prices reach their highs, ski school and rentals book out and lift lines are longest. Book months ahead, and early-season snow cover varies year to year. Source ↗
- Season
Snow season
Ski seasonAbout 72 cm of snow falls in the month.
from the climate normals
Nearby, and something's on
Within 300 km of Mammoth Lakes — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Mammoth Lakes?
Mammoth Lakes in December — FAQ
- Is December a good time to visit Mammoth Lakes?
- December in Mammoth Lakes: cold, rainy, with clean air — an excellent time to visit. It ranks #4 of 12 months for Mammoth Lakes on SeasonMap's comfort score (82/100).
- What is the weather like in Mammoth Lakes in December?
- In December, Mammoth Lakes averages a daily high of 5.7°C and a low of -9°C, with about 96.1 mm of rain over roughly 7.7 rainy days.
- What is the air quality in Mammoth Lakes in December?
- Mammoth Lakes has a mean US Air Quality Index of about 39 in December.
- Does it snow in Mammoth Lakes in December?
- Mammoth Lakes sees roughly 72.3 cm of snowfall in December.
Within 300 km: Santa Cruz, California's Monarch butterflies around 15 Oct – 15 Feb, and Monterey's Monarchs at Pacific Grove around 20 Oct – 28 Feb.