Hardly any U.S. towns see fresher July days than Mammoth
Deep winter brings January lows near 16°. Precipitation is light here, less than falls on 87% of U.S. towns. January has warmed most since 1901–2000, part of a 1.4° rise. Plan time outside from June to September, when highs sit at 63–74°.
A year in Mammoth at a glance
Each month’s typical high and low, and what it brings.
What stands out about Mammoth’s climate
Compared with towns across the U.S., with Mammoth’s place in Montana beside it.
What a year in Mammoth feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 117 frost-free days a year
In half of years the last 32° night comes by May 24 and the first by September 22. Frost dates and degree days from Laurin 2ne, MT, 21 miles away.
The 2023 USDA map puts Mammoth’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −16°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 25 inches of rain a year
June is the wettest month and January the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Mammoth
98% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from September through June.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Laurin 2ne, MT.
Living with Mammoth’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
117 frost-free days in zone 5a. The last frost comes by May 24 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 22.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September.
Parks & trails →Of the yearly building losses FEMA expects in Mammoth from natural hazards, avalanches are the largest share (67%); heat waves, cold waves, winter storms and ice storms together are 5%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Mammoth and similar climates
TownRatings has no climate map of the towns around Mammoth yet.
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Mammoth averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.0°).
A bigger shift than in 53% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Mammoth compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Mammoth’s place among Montana’s.
Mammoth weather by month
Highs, lows and precipitation from NOAA’s grid at Mammoth’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 32° | 16° | 1.4" | 16° – 30° |
| February | 33° | 15° | 1.5" | 15° – 33° |
| March | 40° | 21° | 2.0" | 24° – 37° |
| April | 46° | 26° | 2.9" | 30° – 41° |
| May | 55° | 34° | 3.7" | 40° – 49° |
| June | 64° | 41° | 3.7" | 47° – 59° |
| July | 74° | 48° | 1.5" | 51° – 68° |
| August | 73° | 47° | 1.5" | 53° – 64° |
| September | 63° | 40° | 1.8" | 48° – 56° |
| October | 49° | 30° | 2.2" | 32° – 46° |
| November | 38° | 21° | 1.6" | 21° – 38° |
| December | 31° | 15° | 1.6" | 16° – 27° |
| Year | 50° | 30° | 25.2" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 15° to 33°. September is the most reliable, staying within 8°.
Where Mammoth’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Mammoth’s center.
- Frost dates, heating and cooling: Laurin 2ne, MT, 21 miles away.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Mammoth’s climate
What is the weather like in Mammoth?
A typical July afternoon reaches 74°, a January night drops to 16°. Colder January nights than 80% of U.S. towns; cooler July afternoons than all but 167 U.S. towns.
How cold does it get in Mammoth in winter?
December nights average 15°. About 184 nights a year reach 32° or below and 13 reach 0° or below. In the coldest December of the last 30 years the month averaged 16°.
How hot does it get in Mammoth?
July, with a typical high of 74° and a low of 48°. About 1 days a year reach 90° (Laurin 2ne, MT).
When is the first and last frost in Mammoth?
In half of years the last spring frost (32°) comes by May 24 and the first fall frost by September 22, about 117 frost-free days, at Laurin 2ne, MT.
What growing zone is Mammoth in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −16°.
What is the best time of year to visit Mammoth?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Mammoth getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 53% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Mammoth.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.