Photo: Derek Jensen (Tysto) · Public domainA middle-of-the-road climate: Decatur is close to most U.S. towns on every count
High summer brings afternoon highs near 84°. A year here swings 66° from midwinter lows to midsummer highs. In January, nights here are colder than in 67% of U.S. towns. The frost-free window for a garden runs roughly April 23 to October 19.
A year in Decatur at a glance
Each month’s typical high and low, and what it brings.
What stands out about Decatur’s climate
Compared with towns across the U.S., with Decatur’s place in Indiana beside it.
What a year in Decatur feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 178 frost-free days a year
In half of years the last 32° night comes by April 23 and the first by October 19. Frost and day counts come from NOAA’s station at Decatur 1 N, IN, 1.4 miles from the town’s center, at about the same height.
The 2023 USDA map puts Decatur’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −7°. 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 28 inches of snow a winter
Snow, measured at Decatur 1 N, IN, falls mostly in January. Precipitation (rain plus melted snow) adds up to 40 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 127 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Decatur
88% of the work is heating, so the furnace matters far more than the air conditioner. 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 Decatur 1 N, IN.
Living with Decatur’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
178 frost-free days in zone 6a. The last frost comes by Apr 23 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: May, June, August, September and October. 1.5 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Decatur from natural hazards, river flooding is the largest share (60%); heat waves, cold waves, winter storms and ice storms together are 8%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Decatur and similar climates
TownRatings has no climate map of the towns around Decatur yet.
Climates most like Decatur’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 |
|---|---|---|---|---|
| Decatur, IN | 19° | 84° | 40" | 28" |
| Struthers, OH | 19° | 84° | 41" | 28" |
| New Castle, PA | 20° | 84° | 42" | 28" |
| Markham, IL | 17° | 84° | 39" | 28" |
| Claverack, NY | 16° | 84° | 42" | 31" |
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 Decatur averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.6°).
A bigger shift than in 54% 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 Decatur compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Decatur’s place among Indiana’s.
Decatur weather by month
Highs, lows and precipitation from NOAA’s grid at Decatur’s center; snow, wet days and snow on the ground from Decatur 1 N, IN. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 33° | 19° | 2.6" | 9.2" | 11 | 14 | 16° – 38° |
| February | 37° | 21° | 2.1" | 7.5" | 9 | 11 | 17° – 39° |
| March | 48° | 30° | 2.8" | 4.2" | 11 | 4 | 30° – 53° |
| April | 61° | 39° | 3.9" | 0.5" | 13 | 0 | 43° – 56° |
| May | 72° | 50° | 4.6" | 0.0" | 13 | 0 | 54° – 67° |
| June | 81° | 60° | 4.5" | 0.0" | 12 | 0 | 65° – 74° |
| July | 84° | 63° | 4.4" | 0.0" | 10 | 0 | 69° – 79° |
| August | 82° | 61° | 4.0" | 0.0" | 9 | 0 | 67° – 77° |
| September | 77° | 53° | 3.0" | 0.0" | 8 | 0 | 61° – 69° |
| October | 64° | 43° | 2.9" | 0.0" | 10 | 0 | 50° – 60° |
| November | 50° | 33° | 3.1" | 1.2" | 10 | 2 | 34° – 48° |
| December | 38° | 24° | 2.5" | 5.5" | 11 | 8 | 18° – 41° |
| Year | 60° | 41° | 40.3" | 28.1" | 127 | 38 |
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 Decatur’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 Decatur’s center.
- Snow: Decatur 1 N, IN (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Decatur 1 N, IN, 1.4 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 Decatur’s climate
What is the weather like in Decatur?
A typical July afternoon reaches 84°, a January night drops to 19°, and about 28 inches of snow falls in a normal winter. Colder January nights than 67% of U.S. towns; cooler July afternoons than 59% of U.S. towns.
How cold does it get in Decatur in winter?
January nights average 19°. About 127 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 16°.
How much snow does Decatur get?
About 28 inches in a normal winter at Decatur 1 N, IN, most of it in January, with snow on the ground about 38 days a year.
How hot does it get in Decatur?
July, with a typical high of 84° and a low of 63°. About 18 days a year reach 90° (Decatur 1 N, IN).
When is the first and last frost in Decatur?
In half of years the last spring frost (32°) comes by April 23 and the first fall frost by October 19, about 178 frost-free days, at Decatur 1 N, IN.
What growing zone is Decatur in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −7°.
What is the best time of year to visit Decatur?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Decatur getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 54% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Decatur.
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.