Photo: Nyttend · Public domainNo extremes in Sullivan Township: its weather tracks the middle of U.S. towns
Nights in January average 20°. Winter nights are cold: in January they are colder than in 62% of U.S. towns. Compared with 1901–2000, the average now sits 1.0° higher. Keep the boiler serviced for the months from November to March, which average under 50°.
A year in Sullivan Township at a glance
Each month’s typical high and low, and what it brings.
What stands out about Sullivan Township’s climate
Compared with towns across the U.S., with Sullivan Township’s place in Illinois beside it.
What a year in Sullivan Township feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 187 frost-free days a year
In half of years the last 32° night comes by April 15 and the first by October 22. Frost and day counts come from NOAA’s station at Sullivan 3s, IL, 3 miles from the town’s center, at about the same height.
The 2023 USDA map puts Sullivan Township’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −6°. 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 13 inches of snow a winter
Snow, measured at Sullivan 3s, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 40 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 103 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Sullivan Township
83% of the work is heating. Months averaging under 55° run from November 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 Sullivan 3s, IL.
Living with Sullivan Township’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
187 frost-free days in zone 6a. The last frost comes by Apr 15 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 22.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 3.2 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Sullivan Township from natural hazards, river flooding is the largest share (45%); heat waves, cold waves, winter storms and ice storms together are 21%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Sullivan Township and its neighbors
Every town next door is within a degree of Sullivan Township in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Sullivan Township’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 |
|---|---|---|---|---|
| Sullivan Township, IL | 20° | 86° | 40" | 13" |
| Trotwood, OH | 21° | 85° | 41" | 12" |
| Macon, MO | 18° | 87° | 42" | 15" |
| Fort Madison, IA | 17° | 86° | 39" | 18" |
| Connersville, IN | 20° | 85° | 44" | 16" |
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 Sullivan Township averaged 1.0° warmer than the 1900s. The biggest change is in December (+2.1°).
A smaller shift than in 76% 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 Sullivan Township compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Sullivan Township’s place among Illinois’.
Sullivan Township weather by month
Highs, lows and precipitation from NOAA’s grid at Sullivan Township’s center; snow, wet days and snow on the ground from Sullivan 3s, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 35° | 20° | 2.4" | 5.2" | 8 | 20° – 39° |
| February | 40° | 23° | 2.1" | 2.4" | 8 | 19° – 41° |
| March | 52° | 33° | 2.8" | 1.0" | 9 | 35° – 55° |
| April | 64° | 42° | 4.4" | 0.2" | 10 | 45° – 59° |
| May | 74° | 53° | 4.5" | 0.0" | 12 | 58° – 72° |
| June | 83° | 62° | 4.5" | 0.0" | 10 | 68° – 76° |
| July | 86° | 65° | 4.2" | 0.0" | 8 | 70° – 82° |
| August | 85° | 63° | 3.1" | 0.0" | 7 | 69° – 79° |
| September | 79° | 56° | 3.0" | 0.0" | 7 | 62° – 72° |
| October | 67° | 44° | 3.4" | 0.0" | 8 | 51° – 61° |
| November | 52° | 34° | 3.4" | 0.4" | 9 | 35° – 50° |
| December | 40° | 25° | 2.4" | 3.7" | 8 | 18° – 41° |
| Year | 63° | 43° | 40.1" | 12.9" | 103 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 18° to 41°. June is the most reliable, staying within 8°.
Where Sullivan Township’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 Sullivan Township’s center.
- Snow: Sullivan 3s, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Sullivan 3s, IL, 3 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 Sullivan Township’s climate
What is the weather like in Sullivan Township?
A typical July afternoon reaches 86°, a January night drops to 20°, and about 13 inches of snow falls in a normal winter. Colder January nights than 62% of U.S. towns; hotter July afternoons than 54% of U.S. towns.
How cold does it get in Sullivan Township in winter?
January nights average 20°. About 122 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 20°.
How much snow does Sullivan Township get?
About 13 inches in a normal winter at Sullivan 3s, IL, most of it in January.
How hot does it get in Sullivan Township?
July, with a typical high of 86° and a low of 65°. About 22 days a year reach 90° (Sullivan 3s, IL).
When is the first and last frost in Sullivan Township?
In half of years the last spring frost (32°) comes by April 15 and the first fall frost by October 22, about 187 frost-free days, at Sullivan 3s, IL.
What growing zone is Sullivan Township in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −6°.
What is the best time of year to visit Sullivan Township?
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 Sullivan Township getting warmer?
Yes: 1991–2020 averaged 1.0° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 76% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Sullivan Township.
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.