Adam's, J. C., Stone Barn · Photo: CrazyforMontana · CC BY-SA 3.0Sun River is among the driest of U.S. towns: 12 inches of precipitation a year
Midwinter brings lows of about 14°. By January nights alone, it runs colder than 87% of U.S. towns. Compared with 1901–2000, the average now sits 1.2° higher. Warm coats and heating bills mark the months from October to April, when means dip under 50°.
A year in Sun River at a glance
Each month’s typical high and low, and what it brings.
What stands out about Sun River’s climate
Compared with towns across the U.S., with Sun River’s place in Montana beside it.
What a year in Sun River feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 96 frost-free days a year
In half of years the last 32° night comes by June 2 and the first by September 10. Frost and day counts come from NOAA’s station at Sun Rvr 4 S, MT, 4 miles from the town’s center, 180 ft higher.
The 2023 USDA map puts Sun River’s center in zone 4a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −27°. 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 49 inches of snow a winter
Snow, measured at Power 6 Se, MT, falls mostly in April. Precipitation (rain plus melted snow) adds up to 12 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 93 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Sun River
98% 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 Sun Rvr 4 S, MT.
Living with Sun River’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
96 frost-free days in zone 4a. The last frost comes by Jun 2 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 10.
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 Sun River from natural hazards, river flooding is the largest share (45%); heat waves, cold waves, winter storms and ice storms together are 37%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Sun River and similar climates
TownRatings has no climate map of the towns around Sun River yet.
Climates most like Sun River’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Sun River, MT | 14° | 84° | 12" | 49" |
| Cody, WY | 14° | 85° | 11" | 45" |
| Rigby, ID | 12° | 85° | 12" | 66" |
| Doney Park, AZ | 17° | 86° | 16" | 52" |
| Taos, NM | 11° | 84° | 13" | 28" |
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 Sun River averaged 1.2° warmer than the 1900s. The biggest change is in January (+4.9°).
A smaller shift than in 62% 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 Sun River compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Sun River’s place among Montana’s.
Sun River weather by month
Highs, lows and precipitation from NOAA’s grid at Sun River’s center; snow, wet days and snow on the ground from Power 6 Se, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 36° | 14° | 0.3" | 6.1" | 7 | 21 | 13° – 36° |
| February | 38° | 15° | 0.4" | 5.2" | 7 | 17 | −1° – 39° |
| March | 47° | 22° | 0.5" | 7.9" | 8 | 12 | 17° – 44° |
| April | 56° | 30° | 1.4" | 9.4" | 10 | 6 | 37° – 48° |
| May | 65° | 38° | 2.0" | 3.1" | 11 | 2 | 47° – 56° |
| June | 73° | 46° | 2.5" | 1.2" | 11 | 0 | 56° – 65° |
| July | 84° | 51° | 1.1" | 0.0" | 7 | 0 | 57° – 75° |
| August | 83° | 49° | 1.0" | 0.4" | 7 | 0 | 60° – 70° |
| September | 72° | 42° | 1.1" | 0.6" | 7 | 0 | 52° – 63° |
| October | 58° | 32° | 0.7" | 4.0" | 7 | 3 | 35° – 52° |
| November | 44° | 23° | 0.5" | 6.0" | 6 | 10 | 22° – 43° |
| December | 36° | 16° | 0.3" | 5.1" | 7 | 17 | 14° – 35° |
| Year | 58° | 31° | 11.7" | 49.0" | 93 | 88 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from -1° to 39°. May is the most reliable, staying within 9°.
Where Sun River’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 Sun River’s center.
- Snow: Power 6 Se, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Sun Rvr 4 S, MT, 4 miles from the town’s center, 180 ft higher; 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 Sun River’s climate
What is the weather like in Sun River?
A typical July afternoon reaches 84°, a January night drops to 14°, and about 49 inches of snow falls in a normal winter. Colder January nights than 87% of U.S. towns; cooler July afternoons than 65% of U.S. towns.
How cold does it get in Sun River in winter?
January nights average 14°. About 170 nights a year reach 32° or below and 25 reach 0° or below. In the coldest January of the last 30 years the month averaged 13°.
How much snow does Sun River get?
About 49 inches in a normal winter at Power 6 Se, MT, most of it in April, with snow on the ground about 88 days a year.
How hot does it get in Sun River?
July, with a typical high of 84° and a low of 51°. About 18 days a year reach 90° (Sun Rvr 4 S, MT).
When is the first and last frost in Sun River?
In half of years the last spring frost (32°) comes by June 2 and the first fall frost by September 10, about 96 frost-free days, at Sun Rvr 4 S, MT.
What growing zone is Sun River in?
Zone 4a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −27°.
What is the best time of year to visit Sun River?
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 Sun River getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 62% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Sun River.
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.