Union Grove, Wisconsin climate: Normal weather by month, frost dates and records
Union Grove's normal year runs from 12°F January nights to 81°F July afternoons, with 35.3 inches of precipitation and 41 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.0°C, January lows of −11°C, July highs of 27°C, 896 mm of precipitation a year.
- NOAA stationUnion Grove
- Station IDUSC00478723
- Location42.69°N 88.03°W
- Elevation730 ft (223 m)
- From the centerunder 1 mile
- Population5,241
On October 23, the normal high in Union Grove is 57°F and the normal low 36°F, and the chance of measurable rain or snow is 31%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Union Grove.
- Jan 28° 12°
- Feb 32° 15°
- Mar 43° 25°
- Apr 55° 35°
- May 66° 45°
- Jun 76° 56°
- Jul 81° 61°
- Aug 79° 58°
- Sep 72° 50°
- Oct 60° 39°
- Nov 45° 28°
- Dec 34° 18°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Union Grove each month?
July is the warmest month, with normal highs of 81°F; January the coldest, with normal lows of 12°F. The most precipitation falls in June (4.50 in), the least in February (1.48 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 28°F | 12°F | 19.9°F | 1.76 | 13.0 | 9 | <1 | 29 | 9 h 20 min |
| February | 32°F | 15°F | 23.5°F | 1.48 | 11.0 | 7 | <1 | 26 | 10 h 30 min |
| March | 43°F | 25°F | 33.8°F | 2.10 | 4.9 | 8 | <1 | 24 | 11 h 50 min |
| April | 55°F | 35°F | 44.7°F | 3.51 | 1.7 | 11 | <1 | 11 | 13 h 20 min |
| May | 66°F | 45°F | 55.9°F | 4.13 | 0.0 | 12 | <1 | 1 | 14 h 40 min |
| June | 76°F | 56°F | 66.0°F | 4.50 | 0.0 | 11 | 2 | <1 | 15 h 20 min |
| July | 81°F | 61°F | 70.7°F | 3.54 | 0.0 | 9 | 4 | <1 | 15 h |
| August | 79°F | 58°F | 68.6°F | 3.82 | 0.0 | 9 | 2 | <1 | 14 h |
| September | 72°F | 50°F | 61.3°F | 3.39 | 0.0 | 9 | 1 | <1 | 12 h 30 min |
| October | 60°F | 39°F | 49.4°F | 2.94 | 0.1 | 10 | <1 | 7 | 11 h 10 min |
| November | 45°F | 28°F | 36.8°F | 2.38 | 2.1 | 8 | <1 | 19 | 9 h 50 min |
| December | 34°F | 18°F | 25.9°F | 1.73 | 7.7 | 9 | <1 | 28 | 9 h |
| Year (annual) | 56°F | 37°F | 46.4°F | 35.28 | 40.5 | 111 | 9 | 145 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −2°C | −11°C | −6.7°C | 45 mm | 33 cm |
| February | 0°C | −9°C | −4.7°C | 38 mm | 28 cm |
| March | 6°C | −4°C | 1.0°C | 53 mm | 12 cm |
| April | 13°C | 1°C | 7.1°C | 89 mm | 4 cm |
| May | 19°C | 7°C | 13.3°C | 105 mm | 0 cm |
| June | 25°C | 13°C | 18.9°C | 114 mm | 0 cm |
| July | 27°C | 16°C | 21.5°C | 90 mm | 0 cm |
| August | 26°C | 15°C | 20.3°C | 97 mm | 0 cm |
| September | 22°C | 10°C | 16.3°C | 86 mm | 0 cm |
| October | 15°C | 4°C | 9.7°C | 75 mm | 0 cm |
| November | 7°C | −2°C | 2.7°C | 60 mm | 5 cm |
| December | 1°C | −8°C | −3.4°C | 44 mm | 20 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00478723; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Union Grove?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00478723.
When is the last frost in Union Grove?
In Union Grove, the last spring frost (32°F) comes after May 5 in half of years and after May 20 in one year in ten; the first autumn frost comes before October 8 in half of years and before September 27 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 51 year in 10 after May 20; 9 in 10 after April 21
- First autumn frost, half of years before
- October 81 year in 10 before September 27; 9 in 10 before October 23
NOAA puts the median frost-free season at 156 days, and the season without a hard freeze (28°F) at 178 days.
A hard freeze (28°F) comes after April 23 in half of springs and before October 20 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Union Grove in zone 5b in ZIP code 53182, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Union Grove's NOAA station is in zone 5b: the coldest night of a typical year reaches −13°F (22 complete years).
Frost dates for every NOAA station in Wisconsin · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00478723; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Union Grove?
In a normal year in Union Grove, 9 days a year reach 90°F, 145 nights fall to 32°F or colder and 111 days bring measurable precipitation.
- Days at 90°F or more
- 9a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 145a normal year
- Days that stay below freezing
- 54high of 32°F or less
- Days with 0.01 inch of precipitation
- 111a normal year
- Days with 1 inch of snow or more
- 13a normal year
The highest temperature in this station's record (since 1964) is 104°F, on July 6, 2012; the lowest is −25°F, on January 31, 2019.
The wettest calendar year on that record is 2018, with 48.29 in; the snowiest season is 2007–08, with 94.3 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00478723; records: ACIS (NOAA Regional Climate Centers), station USC00478723. Records use complete months only; a month missing more than three days is left out.
How sunny is Union Grove?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Union Grove, 3.9 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 63% | 1.7 |
| February | 67% | 2.6 |
| March | 67% | 3.6 |
| April | 69% | 4.7 |
| May | 70% | 5.5 |
| June | 76% | 6.1 |
| July | 80% | 6.3 |
| August | 79% | 5.4 |
| September | 78% | 4.3 |
| October | 69% | 2.8 |
| November | 66% | 1.9 |
| December | 61% | 1.4 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Union Grove need?
A normal year in Union Grove brings 7,283 heating degree days, 36% more than the median U.S. place (5,373), and 529 cooling degree days, 42% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,455 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,398 | 0 |
| February | 1,162 | 0 |
| March | 968 | 0 |
| April | 613 | 3 |
| May | 308 | 26 |
| June | 80 | 108 |
| July | 18 | 196 |
| August | 28 | 140 |
| September | 159 | 50 |
| October | 490 | 6 |
| November | 848 | 0 |
| December | 1,212 | 0 |
| Year (annual) | 7,283 | 529 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00478723. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Union Grove been warmer than normal lately?
2025 averaged 47.5°F, 1.1°F above the 1991-2020 normal of 46.4°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 48.3°F | +1.9°F | 21.41 | 40.5 |
| 2022 | 46.7°F | +0.3°F | 29.47 | 29.4 |
| 2023 | 49.3°F | +2.9°F | 33.66 | 39.8 |
| 2024 | 50.5°F | +4.1°F | 37.19 | 31.0 |
| 2025 | 47.5°F | +1.1°F | 29.23 | 33.1 |
Source: observed years: ACIS, station USC00478723. A year counts only with all twelve months complete.
How does Union Grove's climate compare?
Union Grove is warmer than 116 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 92. Across the 7,247 U.S. stations with normals, its annual mean of 46.4°F is warmer than 25%.
In the Köppen classification computed from these normals, Union Grove is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Union Grove share this climate record?
3 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Raymond, WI3,974 people · 8 mi N
- Yorkville, WI3,247 people · 3 mi NE
- Eagle Lake, WI1,019 people · 5 mi W
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Union Grove's climate
What is the coldest month in Union Grove?
January, with a normal high of 28°F and a normal low of 12°F. The warmest is July (81°F by day, 61°F at night).
Does it snow in Union Grove?
Yes: 41 inches in a normal year, falling on 18 days with 0.1 inch or more, the most in January (13.0 inches).
What is the rainiest month in Union Grove?
June, with 4.50 in of precipitation in a normal year; the driest is February with 1.48 in.
What plant hardiness zone is Union Grove in?
The USDA's 2023 map puts Union Grove in zone 5b in ZIP code 53182, the nearest ZIP area. By the same method at Union Grove's NOAA station, the coldest night of a typical year reaches −13°F (22 years, 1991-2020): zone 5b.
How late can frost come in Union Grove?
In half of years the last 32°F night comes after May 5; in one year in ten it comes after May 20. Waiting until May 20 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wisconsin climateThe statewide normals and every place in the state
- Paddock Lake, WI8 miles from this station, 47.4°F a year
- Kenosha, WI8 miles from this station, 49.2°F a year
- Rochester, WI10 miles from this station, 46.7°F a year
- Burlington, WI12 miles from this station, 46.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made