Comertown Historic District · Photo: Jon Roanhaus · CC BY-SA 4.0Hardly any U.S. towns see harsher January nights than Westby
July afternoons average 81°. The year swings widely: the coldest month’s nights and the warmest month’s afternoons are 81° apart. It is a dry place: less rain and snow fall here than on 93% of U.S. towns. The outdoor season runs from June to September, with highs of 71–81°.
A year in Westby at a glance
Each month’s typical high and low, and what it brings.
What stands out about Westby’s climate
Compared with towns across the U.S., with Westby’s place in Montana beside it.
What a year in Westby feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 125 frost-free days a year
In half of years the last 32° night comes by May 18 and the first by September 21. Frost and day counts come from NOAA’s station at Westby, MT, 0.4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Westby’s center in zone 3b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −31°. 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 37 inches of snow a winter
Snow, measured at Fortuna 1 W, ND, falls mostly in January, March and December. Precipitation (rain plus melted snow) adds up to 15 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 48 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Westby
97% 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 Westby, MT.
Living with Westby’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
125 frost-free days in zone 3b. The last frost comes by May 18 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 21.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September.
Parks & trails →Cold waves are 58% of the yearly building losses FEMA expects in Westby from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Westby and its neighbors
Every town next door is within a degree of Westby in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Westby’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 |
|---|---|---|---|---|
| Westby, MT | 0° | 81° | 15" | 37" |
| Gunnison, CO | 0° | 82° | 12" | 50" |
| Jamestown, ND | 1° | 82° | 21" | 46" |
| East Grand Forks, MN | −2° | 81° | 23" | 49" |
| 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 Westby averaged 1.6° warmer than the 1900s. The biggest change is in January (+4.8°).
A bigger shift than in 68% 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 Westby compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Westby’s place among Montana’s.
Westby weather by month
Highs, lows and precipitation from NOAA’s grid at Westby’s center; snow, wet days and snow on the ground from Fortuna 1 W, ND. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 20° | 0° | 0.5" | 6.6" | 2 | −3° – 26° |
| February | 24° | 4° | 0.3" | 5.7" | 2 | −7° – 28° |
| March | 37° | 16° | 0.6" | 7.0" | 3 | 12° – 38° |
| April | 54° | 28° | 1.0" | 3.4" | 3 | 30° – 48° |
| May | 66° | 39° | 2.1" | 0.9" | 6 | 48° – 59° |
| June | 74° | 50° | 3.3" | 0.0" | 10 | 58° – 68° |
| July | 81° | 54° | 2.3" | 0.0" | 7 | 61° – 74° |
| August | 81° | 52° | 1.5" | 0.0" | 5 | 61° – 72° |
| September | 71° | 42° | 1.2" | 0.0" | 3 | 51° – 63° |
| October | 54° | 29° | 0.9" | 2.2" | 3 | 33° – 47° |
| November | 36° | 16° | 0.5" | 4.3" | 2 | 13° – 38° |
| December | 24° | 5° | 0.5" | 6.4" | 3 | 2° – 25° |
| Year | 52° | 28° | 14.7" | 36.5" | 48 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from -7° to 28°. June is the most reliable, staying within 10°.
Where Westby’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 Westby’s center.
- Snow: Fortuna 1 W, ND.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Westby, MT, 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 Westby’s climate
What is the weather like in Westby?
A typical July afternoon reaches 81°, a January night drops to 0°, and about 37 inches of snow falls in a normal winter. Colder January nights than all but 44 U.S. towns; cooler July afternoons than 86% of U.S. towns.
How cold does it get in Westby in winter?
January nights average 0°. About 202 nights a year reach 32° or below and 49 reach 0° or below. In the coldest January of the last 30 years the month averaged −3°.
How much snow does Westby get?
About 37 inches in a normal winter at Fortuna 1 W, ND, most of it in January, March and December.
How hot does it get in Westby?
July, with a typical high of 81° and a low of 54°. About 10 days a year reach 90° (Westby, MT).
When is the first and last frost in Westby?
In half of years the last spring frost (32°) comes by May 18 and the first fall frost by September 21, about 125 frost-free days, at Westby, MT.
What growing zone is Westby in?
Zone 3b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −31°.
What is the best time of year to visit Westby?
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 Westby getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Westby.
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.