Few U.S. towns have colder winter nights than Boneau
The warmest part of a July day comes in at 83° on average. It is a dry place: less rain and snow fall here than on 92% of U.S. towns. Compared with 1901–2000, the average now sits 1.7° higher. Picnics, hikes and garden evenings come into their own from June to September, with highs of 70–83°.
A year in Boneau at a glance
Each month’s typical high and low, and what it brings.
What stands out about Boneau’s climate
Compared with towns across the U.S., with Boneau’s place in Montana beside it.
What a year in Boneau feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 128 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by September 25. Frost and day counts come from NOAA’s station at Big Sandy, MT, 14 miles from the town’s center, 470 ft lower.
The 2023 USDA map puts Boneau’s center in zone 4a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −26°. 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 35 inches of snow a winter
Snow, measured at Ft Assiniboine, MT, falls mostly in February. Precipitation (rain plus melted snow) adds up to 16 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 88 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Boneau
94% 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 Big Sandy, MT.
Living with Boneau’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
128 frost-free days in zone 4a. The last frost comes by May 17 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 25.
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 Boneau from natural hazards, river flooding is the largest share (43%); heat waves, cold waves, winter storms and ice storms together are 40%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Boneau and its neighbors
Every town next door is within a degree of Boneau in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Boneau’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 |
|---|---|---|---|---|
| Boneau, MT | 9° | 83° | 16" | 35" |
| Dickinson, ND | 5° | 83° | 16" | 35" |
| Taos, NM | 11° | 84° | 13" | 28" |
| Gypsum, CO | 11° | 86° | 14" | 39" |
| Aberdeen, SD | 3° | 84° | 22" | 43" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Boneau averaged 1.7° warmer than the 1900s. The biggest change is in January (+5.0°).
A bigger shift than in 70% 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 Boneau compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Boneau’s place among Montana’s.
Boneau weather by month
Highs, lows and precipitation from NOAA’s grid at Boneau’s center; snow, wet days and snow on the ground from Ft Assiniboine, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 30° | 9° | 0.5" | 6.4" | 7 | 6° – 34° |
| February | 34° | 10° | 0.5" | 7.3" | 5 | −3° – 37° |
| March | 44° | 19° | 0.6" | 4.0" | 5 | 14° – 40° |
| April | 55° | 30° | 1.3" | 2.7" | 8 | 37° – 46° |
| May | 64° | 39° | 2.5" | 0.7" | 11 | 47° – 57° |
| June | 73° | 46° | 3.3" | 0.0" | 13 | 56° – 64° |
| July | 83° | 51° | 2.0" | 0.0" | 8 | 58° – 74° |
| August | 82° | 50° | 1.3" | 0.0" | 7 | 60° – 71° |
| September | 70° | 41° | 1.4" | 0.0" | 7 | 51° – 61° |
| October | 56° | 30° | 1.3" | 1.9" | 7 | 36° – 49° |
| November | 42° | 20° | 0.7" | 5.2" | 6 | 18° – 40° |
| December | 32° | 11° | 0.5" | 6.4" | 5 | 8° – 32° |
| Year | 55° | 30° | 15.8" | 34.6" | 88 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from -3° to 37°. June is the most reliable, staying within 8°.
Where Boneau’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 Boneau’s center.
- Snow: Ft Assiniboine, MT.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Big Sandy, MT, 14 miles from the town’s center, 470 ft lower; 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 Boneau’s climate
What is the weather like in Boneau?
A typical July afternoon reaches 83°, a January night drops to 9°, and about 35 inches of snow falls in a normal winter. Colder January nights than 95% of U.S. towns; cooler July afternoons than 74% of U.S. towns.
How cold does it get in Boneau in winter?
January nights average 9°. About 180 nights a year reach 32° or below and 29 reach 0° or below. In the coldest January of the last 30 years the month averaged 6°.
How much snow does Boneau get?
About 35 inches in a normal winter at Ft Assiniboine, MT, most of it in February.
How hot does it get in Boneau?
July, with a typical high of 83° and a low of 51°. About 28 days a year reach 90° and 2 reach 100° (Big Sandy, MT).
When is the first and last frost in Boneau?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by September 25, about 128 frost-free days, at Big Sandy, MT.
What growing zone is Boneau in?
Zone 4a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −26°.
What is the best time of year to visit Boneau?
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 Boneau getting warmer?
Yes: 1991–2020 averaged 1.7° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 70% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Boneau.
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.