Photo: Not credited · Public domainBison sits near the bottom of U.S. towns for winter warmth
Expect July afternoons of about 85°. Rain follows the seasons: June brings about 8.7 times as much as January. Precipitation is light here, less than falls on 91% of U.S. towns. Keep the boiler serviced for the months from October to April, which average under 50°.
A year in Bison at a glance
Each month’s typical high and low, and what it brings.
What stands out about Bison’s climate
Compared with towns across the U.S., with Bison’s place in South Dakota beside it.
What a year in Bison feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 144 frost-free days a year
In half of years the last 32° night comes by May 10 and the first by October 1. Frost and day counts come from NOAA’s station at Bison, SD, 0.4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Bison’s center in zone 5a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −20°. 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 40 inches of snow a winter
Snow, measured at Bison, SD, falls mostly in February. Precipitation (rain plus melted snow) adds up to 18 inches a year; June is the wettest month and January the driest. Rain or snow falls on about 57 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Bison
92% 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 Bison, SD.
Living with Bison’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
144 frost-free days in zone 5a. The last frost comes by May 10 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 1.
Months with highs of 62–84° and lows of 40° or more: May, June, August and September. 1.0 miles of trails are waiting.
Parks & trails →Cold waves are 41% of the yearly building losses FEMA expects in Bison from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Bison and its neighbors
Every town next door is within a degree of Bison in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Bison’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 |
|---|---|---|---|---|
| Bison, SD | 8° | 85° | 18" | 40" |
| Havre, MT | 6° | 85° | 13" | 41" |
| Gypsum, CO | 11° | 86° | 14" | 39" |
| Watford City, ND | 4° | 84° | 16" | 50" |
| Taos, NM | 11° | 84° | 13" | 28" |
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 Bison averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.8°).
A smaller shift than in 57% 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 Bison compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Bison’s place among South Dakota’s.
Bison weather by month
Highs, lows and precipitation from NOAA’s grid at Bison’s center; snow, wet days and snow on the ground from Bison, SD. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 28° | 8° | 0.4" | 5.6" | 3 | 9° – 31° |
| February | 32° | 11° | 0.6" | 8.0" | 4 | 1° – 33° |
| March | 43° | 21° | 0.8" | 7.0" | 4 | 20° – 46° |
| April | 55° | 30° | 1.6" | 5.4" | 6 | 36° – 49° |
| May | 66° | 41° | 3.1" | 0.7" | 7 | 48° – 59° |
| June | 76° | 51° | 3.2" | 0.0" | 8 | 59° – 68° |
| July | 85° | 57° | 2.5" | 0.0" | 7 | 62° – 77° |
| August | 84° | 55° | 1.9" | 0.0" | 5 | 63° – 75° |
| September | 74° | 45° | 1.4" | 0.0" | 4 | 53° – 66° |
| October | 58° | 32° | 1.4" | 3.0" | 4 | 37° – 51° |
| November | 42° | 20° | 0.5" | 4.1" | 3 | 18° – 42° |
| December | 31° | 11° | 0.4" | 5.9" | 3 | 9° – 30° |
| Year | 56° | 32° | 17.9" | 39.7" | 57 |
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 33°. June is the most reliable, staying within 10°.
Where Bison’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 Bison’s center.
- Snow: Bison, SD (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Bison, SD, 0.4 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 Bison’s climate
What is the weather like in Bison?
A typical July afternoon reaches 85°, a January night drops to 8°, and about 40 inches of snow falls in a normal winter. Colder January nights than 96% of U.S. towns; cooler July afternoons than 52% of U.S. towns.
How cold does it get in Bison in winter?
January nights average 8°. About 171 nights a year reach 32° or below and 24 reach 0° or below. In the coldest January of the last 30 years the month averaged 9°.
How much snow does Bison get?
About 40 inches in a normal winter at Bison, SD, most of it in February.
How hot does it get in Bison?
July, with a typical high of 85° and a low of 57°. About 28 days a year reach 90° and 3 reach 100° (Bison, SD).
When is the first and last frost in Bison?
In half of years the last spring frost (32°) comes by May 10 and the first fall frost by October 1, about 144 frost-free days, at Bison, SD.
What growing zone is Bison in?
Zone 5a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −20°.
What is the best time of year to visit Bison?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Bison getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 57% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Bison.
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.