Photo: Royalbroil · CC BY-SA 4.0Union sits near the bottom of U.S. towns for July heat
January mornings start at about 12°. Winter nights are cold: in January they are colder than in 91% of U.S. towns. Since 1901–2000, the year has warmed by 1.7°, most of all in December. Plan time outside from May to September, when highs sit at 62–77°.
A year in Union at a glance
Each month’s typical high and low, and what it brings.
What stands out about Union’s climate
Compared with towns across the U.S., with Union’s place in Wisconsin beside it.
What a year in Union feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 150 frost-free days a year
In half of years the last 32° night comes by May 9 and the first by October 6. Frost and day counts come from NOAA’s station at Oconto 4 W, WI, 17 miles from the town’s center, at about the same height.
The 2023 USDA map puts Union’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −14°. 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 53 inches of snow a winter
Snow, measured at Forestville-4e, WI, falls mostly in January, February and December. Precipitation (rain plus melted snow) adds up to 32 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 115 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Union
95% 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 Oconto 4 W, WI.
Living with Union’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
150 frost-free days in zone 5b. The last frost comes by May 9 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 6.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September.
Parks & trails →Of the yearly building losses FEMA expects in Union from natural hazards, river flooding is the largest share (42%); heat waves, cold waves, winter storms and ice storms together are 37%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Union and its neighbors
Brussels has the coldest January nights next door (10°, 2° colder) and Brussels the hottest July afternoons (79°, 2° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Union’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 |
|---|---|---|---|---|
| Union, WI | 12° | 77° | 32" | 53" |
| Alpena, MI | 14° | 78° | 31" | 59" |
| Plattsburgh, NY | 9° | 80° | 34" | 50" |
| Duluth, MN | 5° | 76° | 30" | 56" |
| Milton, VT | 10° | 80° | 40" | 50" |
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 Union averaged 1.7° warmer than the 1900s. The biggest change is in December (+3.1°).
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 Union compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Union’s place among Wisconsin’s.
Union weather by month
Highs, lows and precipitation from NOAA’s grid at Union’s center; snow, wet days and snow on the ground from Forestville-4e, WI. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 26° | 12° | 1.6" | 12.4" | 9 | 23 | 8° – 30° |
| February | 29° | 14° | 1.2" | 12.6" | 8 | 25 | 10° – 32° |
| March | 39° | 23° | 1.8" | 8.1" | 8 | 18 | 20° – 44° |
| April | 50° | 33° | 3.0" | 4.1" | 10 | 4 | 33° – 47° |
| May | 62° | 43° | 3.4" | 0.1" | 11 | 0 | 47° – 59° |
| June | 72° | 54° | 3.9" | 0.0" | 10 | 0 | 60° – 68° |
| July | 77° | 59° | 3.6" | 0.0" | 10 | 0 | 62° – 73° |
| August | 76° | 59° | 3.3" | 0.0" | 9 | 0 | 63° – 72° |
| September | 69° | 51° | 3.3" | 0.0" | 10 | 0 | 54° – 65° |
| October | 56° | 40° | 3.1" | 0.2" | 12 | 0 | 44° – 54° |
| November | 43° | 30° | 2.2" | 1.6" | 9 | 2 | 28° – 43° |
| December | 31° | 19° | 1.9" | 13.6" | 10 | 18 | 14° – 35° |
| Year | 52° | 36° | 32.3" | 52.7" | 115 | 91 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 20° to 44°. June is the most reliable, staying within 8°.
Where Union’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 Union’s center.
- Snow: Forestville-4e, WI.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Oconto 4 W, WI, 17 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 Union’s climate
What is the weather like in Union?
A typical July afternoon reaches 77°, a January night drops to 12°, and about 53 inches of snow falls in a normal winter. Colder January nights than 91% of U.S. towns; cooler July afternoons than 97% of U.S. towns.
How cold does it get in Union in winter?
January nights average 12°. About 169 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 8°.
How much snow does Union get?
About 53 inches in a normal winter at Forestville-4e, WI, most of it in January, February and December, with snow on the ground about 91 days a year.
How hot does it get in Union?
July, with a typical high of 77° and a low of 59°. About 4 days a year reach 90° (Oconto 4 W, WI).
When is the first and last frost in Union?
In half of years the last spring frost (32°) comes by May 9 and the first fall frost by October 6, about 150 frost-free days, at Oconto 4 W, WI.
What growing zone is Union in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −14°.
What is the best time of year to visit Union?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Union 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 Union.
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.