Dry weather: only 16 inches of rain and melted snow a year in Unionville, less than in 92% of U.S. towns
The warmest part of a July day comes in at 81° on average. June is the wettest month, January the driest. In July, afternoons here are cooler than in 90% of U.S. towns. Picnics, hikes and garden evenings come into their own from June to September, with highs of 69–81°.
A year in Unionville at a glance
Each month’s typical high and low, and what it brings.
What stands out about Unionville’s climate
Compared with towns across the U.S., with Unionville’s place in Montana beside it.
What a year in Unionville feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 100 frost-free days a year
In half of years the last 32° night comes by June 4 and the first by September 14. Frost and day counts come from NOAA’s station at Austin 1 W, MT, 11 miles from the town’s center, 140 ft lower.
The 2023 USDA map puts Unionville’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 16 inches of rain a year
June is the wettest month and January the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Unionville
99% 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 Austin 1 W, MT.
Living with Unionville’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
100 frost-free days in zone 5a. The last frost comes by Jun 4 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 14.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September. 1.8 miles of trails are waiting.
Parks & trails →Cold waves are 30% of the yearly building losses FEMA expects in Unionville from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Unionville and similar climates
TownRatings has no climate map of the towns around Unionville 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 Unionville averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.4°).
A bigger shift than in 52% 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 Unionville compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Unionville’s place among Montana’s.
Unionville weather by month
Highs, lows and precipitation from NOAA’s grid at Unionville’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 33° | 16° | 0.7" | 15° – 32° |
| February | 35° | 17° | 0.8" | 10° – 36° |
| March | 44° | 24° | 1.0" | 24° – 42° |
| April | 52° | 30° | 1.7" | 35° – 46° |
| May | 62° | 38° | 2.4" | 44° – 54° |
| June | 70° | 45° | 2.7" | 52° – 64° |
| July | 81° | 51° | 1.4" | 56° – 73° |
| August | 80° | 50° | 1.2" | 59° – 69° |
| September | 69° | 43° | 1.3" | 52° – 60° |
| October | 54° | 33° | 1.3" | 36° – 50° |
| November | 40° | 23° | 1.1" | 23° – 40° |
| December | 32° | 16° | 0.8" | 15° – 31° |
| Year | 54° | 32° | 16.4" |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 10° to 36°. September is the most reliable, staying within 9°.
Where Unionville’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 Unionville’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Austin 1 W, MT, 11 miles from the town’s center, 140 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 Unionville’s climate
What is the weather like in Unionville?
A typical July afternoon reaches 81°, a January night drops to 16°. Colder January nights than 79% of U.S. towns; cooler July afternoons than 90% of U.S. towns.
How cold does it get in Unionville in winter?
December nights average 16°. About 204 nights a year reach 32° or below and 19 reach 0° or below. In the coldest December of the last 30 years the month averaged 15°.
How hot does it get in Unionville?
July, with a typical high of 81° and a low of 51°. About 4 days a year reach 90° (Austin 1 W, MT).
When is the first and last frost in Unionville?
In half of years the last spring frost (32°) comes by June 4 and the first fall frost by September 14, about 100 frost-free days, at Austin 1 W, MT.
What growing zone is Unionville 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 Unionville?
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 Unionville getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Unionville.
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.