Nights turn raw in Union Star each January, colder than in 75% of U.S. towns
On a normal July day the thermometer tops out near 87°. It is a dry place: less rain and snow fall here than on 66% of U.S. towns. Compared with 1901–2000, the average now sits 0.8° higher. Homes need heating from November to March, the months averaging under 50°.
A year in Union Star at a glance
Each month’s typical high and low, and what it brings.
What stands out about Union Star’s climate
Compared with towns across the U.S., with Union Star’s place in Missouri beside it.
What a year in Union Star feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 184 frost-free days a year
In half of years the last 32° night comes by April 17 and the first by October 19. Frost and day counts come from NOAA’s station at Cosby 2w, MO, 10 miles from the town’s center, at about the same height.
The 2023 USDA map puts Union Star’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −9°. 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 18 inches of snow a winter
Snow, measured at King City, MO, falls mostly in December. Precipitation (rain plus melted snow) adds up to 38 inches a year; May is the wettest month and January the driest. Rain or snow falls on about 71 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Union Star
83% of the work is heating. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Cosby 2w, MO.
Living with Union Star’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
184 frost-free days in zone 6a. The last frost comes by Apr 17 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 19.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October.
Parks & trails →Of the yearly building losses FEMA expects in Union Star from natural hazards, river flooding is the largest share (38%); heat waves, cold waves, winter storms and ice storms together are 15%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Union Star and its neighbors
Every town next door is within a degree of Union Star in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Union Star’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 Star, MO | 17° | 87° | 38" | 18" |
| Fort Madison, IA | 17° | 86° | 39" | 18" |
| Quincy, IL | 19° | 87° | 39" | 17" |
| Terre Haute, IN | 21° | 87° | 43" | 15" |
| Van Wert, OH | 19° | 84° | 39" | 17" |
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 Star averaged 0.8° warmer than the 1900s. The biggest change is in December (+2.1°).
A smaller shift than in 92% 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 Star compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Union Star’s place among Missouri’s.
Union Star weather by month
Highs, lows and precipitation from NOAA’s grid at Union Star’s center; snow, wet days and snow on the ground from King City, MO. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 35° | 17° | 1.0" | 4.2" | 4 | 19° – 38° |
| February | 41° | 21° | 1.3" | 3.9" | 4 | 21° – 41° |
| March | 53° | 31° | 2.3" | 3.0" | 6 | 35° – 57° |
| April | 64° | 41° | 3.9" | 0.5" | 8 | 44° – 59° |
| May | 74° | 52° | 5.3" | 0.0" | 9 | 58° – 72° |
| June | 83° | 62° | 5.3" | 0.0" | 9 | 69° – 76° |
| July | 87° | 66° | 4.9" | 0.0" | 7 | 72° – 83° |
| August | 86° | 64° | 4.1" | 0.0" | 6 | 69° – 80° |
| September | 78° | 55° | 3.7" | 0.0" | 5 | 61° – 72° |
| October | 66° | 43° | 3.1" | 0.1" | 5 | 48° – 59° |
| November | 52° | 31° | 2.0" | 1.2" | 5 | 33° – 51° |
| December | 40° | 22° | 1.5" | 5.0" | 4 | 16° – 37° |
| Year | 63° | 42° | 38.3" | 17.9" | 71 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 35° to 57°. June is the most reliable, staying within 8°.
Where Union Star’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 Star’s center.
- Snow: King City, MO.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Cosby 2w, MO, 10 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 Star’s climate
What is the weather like in Union Star?
A typical July afternoon reaches 87°, a January night drops to 17°, and about 18 inches of snow falls in a normal winter. Colder January nights than 75% of U.S. towns; hotter July afternoons than 62% of U.S. towns.
How cold does it get in Union Star in winter?
January nights average 17°. About 130 nights a year reach 32° or below and 9 reach 0° or below. In the coldest January of the last 30 years the month averaged 19°.
How much snow does Union Star get?
About 18 inches in a normal winter at King City, MO, most of it in December.
How hot does it get in Union Star?
July, with a typical high of 87° and a low of 66°. About 33 days a year reach 90° and 2 reach 100° (Cosby 2w, MO).
When is the first and last frost in Union Star?
In half of years the last spring frost (32°) comes by April 17 and the first fall frost by October 19, about 184 frost-free days, at Cosby 2w, MO.
What growing zone is Union Star in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −9°.
What is the best time of year to visit Union Star?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Union Star getting warmer?
Yes: 1991–2020 averaged 0.8° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 92% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Union Star.
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.