Three Forks of the Missouri · Photo: Mike Cline · Public domainThree Forks sits near the bottom of U.S. towns for precipitation, with 11 inches a year
January mornings start at about 14°. The seasons are far apart: from a winter night to a summer afternoon the average spans 73°. Winter nights are cold: in January they are colder than in 88% of U.S. towns. Central heating does most of its work from October to April, in months below 50° on average.
A year in Three Forks at a glance
Each month’s typical high and low, and what it brings.
What stands out about Three Forks’ climate
Compared with towns across the U.S., with Three Forks’ place in Montana beside it.
What a year in Three Forks feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 139 frost-free days a year
In half of years the last 32° night comes by May 9 and the first by September 27. Frost and day counts come from NOAA’s station at Trident, MT, 5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Three Forks’ center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −21°. 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 11 inches of rain a year
June is the wettest month and February the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Three Forks
96% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Trident, MT.
Living with Three Forks’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
139 frost-free days in zone 4b. The last frost comes by May 9 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 27.
Months with highs of 62–84° and lows of 40° or more: June and September. 0.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Three Forks from natural hazards, avalanches are the largest share (73%); heat waves, cold waves, winter storms and ice storms together are 6%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Three Forks and similar climates
TownRatings has no climate map of the towns around Three Forks 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 Three Forks averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.1°).
A bigger shift than in 50% 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 Three Forks compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Three Forks’ place among Montana’s.
Three Forks weather by month
Highs, lows and precipitation from NOAA’s grid at Three Forks’ center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 36° | 14° | 0.3" | 15° – 33° |
| February | 39° | 16° | 0.2" | 12° – 37° |
| March | 49° | 24° | 0.6" | 24° – 42° |
| April | 58° | 31° | 1.2" | 39° – 48° |
| May | 67° | 39° | 1.8" | 49° – 57° |
| June | 76° | 46° | 2.3" | 56° – 67° |
| July | 86° | 51° | 1.1" | 59° – 76° |
| August | 85° | 49° | 0.9" | 61° – 71° |
| September | 74° | 41° | 0.9" | 54° – 62° |
| October | 60° | 31° | 0.8" | 37° – 51° |
| November | 44° | 21° | 0.5" | 22° – 41° |
| December | 35° | 14° | 0.4" | 16° – 30° |
| Year | 59° | 31° | 10.8" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 37°. May is the most reliable, staying within 8°.
Where Three Forks’ 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 Three Forks’ center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Trident, MT, 5 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- 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 Three Forks’ climate
What is the weather like in Three Forks?
A typical July afternoon reaches 86°, a January night drops to 14°. Colder January nights than 88% of U.S. towns; hotter July afternoons than 56% of U.S. towns.
How cold does it get in Three Forks in winter?
December nights average 14°. About 174 nights a year reach 32° or below and 15 reach 0° or below. In the coldest December of the last 30 years the month averaged 16°.
How hot does it get in Three Forks?
July, with a typical high of 86° and a low of 51°. About 25 days a year reach 90° and 1 reach 100° (Trident, MT).
When is the first and last frost in Three Forks?
In half of years the last spring frost (32°) comes by May 9 and the first fall frost by September 27, about 139 frost-free days, at Trident, MT.
What growing zone is Three Forks in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −21°.
What is the best time of year to visit Three Forks?
By one simple rule (highs of 62–84° and lows of 40° or more), June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Three Forks getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 50% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Three Forks.
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.