Decatur weather in October: Decatur, Illinois: normal highs, lows, rain and records for October
Decatur in October has a normal high of 66°F and a normal low of 44°F, a daily mean of 55°F, falling from 73°F on the 1st to 59°F by the 31st. Measurable precipitation falls on 10 days in a normal October, 3.18 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 19°C and low of 7°C, 81 mm of precipitation in October.
- NOAA stationDecatur Airport
- Station IDUSW00003887
- Location39.83°N 88.87°W
- Elevation675 ft (206 m)
- From the center4 miles
- Population68,763
- Jan 35° 20°
- Feb 40° 23°
- Mar 52° 32°
- Apr 64° 42°
- May 74° 53°
- Jun 83° 62°
- Jul 86° 66°
- Aug 84° 63°
- Sep 79° 55°
- Oct 66° 44°
- Nov 51° 34°
- Dec 40° 25°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Decatur in October?
The normal high is 66°F and the normal low 44°F, for a daily mean of 55.2°F. October is 11.8°F cooler than September and 12.5°F warmer than November. October is the 6th warmest month of the year in Decatur and the 5th wettest. Across the month the normal high falls 14°F, from 73°F on October 1 to 59°F on October 31. From one year to the next October's mean temperature typically moves about 2.4°F either way (NOAA's standard deviation), so roughly two Octobers in three average between 53°F and 58°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 32%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| October 1 | 73°F | 49°F | 30% | 16% |
| October 8 | 70°F | 47°F | 31% | 17% |
| October 15 | 67°F | 45°F | 32% | 18% |
| October 22 | 63°F | 43°F | 32% | 18% |
| October 31 | 59°F | 40°F | 31% | 17% |
Every day of October: normal high, low and chance of precipitation (warmest afternoon October 1, coldest night October 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| October 1 | 73°F | 49°F | 30% | 16% | 11 h 50 min |
| October 2 | 73°F | 49°F | 31% | 16% | 11 h 50 min |
| October 3 | 72°F | 49°F | 31% | 16% | 11 h 40 min |
| October 4 | 72°F | 48°F | 31% | 16% | 11 h 40 min |
| October 5 | 72°F | 48°F | 31% | 16% | 11 h 40 min |
| October 6 | 71°F | 48°F | 31% | 17% | 11 h 40 min |
| October 7 | 71°F | 47°F | 31% | 17% | 11 h 30 min |
| October 8 | 70°F | 47°F | 31% | 17% | 11 h 30 min |
| October 9 | 70°F | 47°F | 31% | 17% | 11 h 30 min |
| October 10 | 69°F | 46°F | 31% | 17% | 11 h 30 min |
| October 11 | 69°F | 46°F | 31% | 17% | 11 h 20 min |
| October 12 | 68°F | 46°F | 32% | 17% | 11 h 20 min |
| October 13 | 68°F | 45°F | 32% | 17% | 11 h 20 min |
| October 14 | 67°F | 45°F | 32% | 18% | 11 h 20 min |
| October 15 | 67°F | 45°F | 32% | 18% | 11 h 10 min |
| October 16 | 66°F | 44°F | 32% | 18% | 11 h 10 min |
| October 17 | 66°F | 44°F | 32% | 18% | 11 h 10 min |
| October 18 | 65°F | 44°F | 32% | 18% | 11 h 10 min |
| October 19 | 65°F | 43°F | 32% | 18% | 11 h |
| October 20 | 64°F | 43°F | 32% | 18% | 11 h |
| October 21 | 64°F | 43°F | 32% | 18% | 11 h |
| October 22 | 63°F | 43°F | 32% | 18% | 11 h |
| October 23 | 63°F | 42°F | 31% | 18% | 10 h 50 min |
| October 24 | 62°F | 42°F | 31% | 18% | 10 h 50 min |
| October 25 | 62°F | 42°F | 31% | 18% | 10 h 50 min |
| October 26 | 61°F | 41°F | 31% | 18% | 10 h 50 min |
| October 27 | 61°F | 41°F | 31% | 18% | 10 h 40 min |
| October 28 | 60°F | 41°F | 31% | 18% | 10 h 40 min |
| October 29 | 60°F | 40°F | 31% | 18% | 10 h 40 min |
| October 30 | 59°F | 40°F | 31% | 17% | 10 h 40 min |
| October 31 | 59°F | 40°F | 31% | 17% | 10 h 30 min |
- Normal high
- 66°FOctober average
- Normal low
- 44°FOctober average
- Precipitation
- 3.18 inmonth total
- Days with precipitation
- 100.01 inch or more
- Nights at 32°F or colder
- 3
- Daylight
- 11 h 50 min to 10 h 30 minOctober 1 to October 31
- Days at 70°F or more
- 12
- Days at 80°F or more
- 4
- Sunshine
- 74%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00003887; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Decatur in October?
On a given October day the chance of 0.01 inch or more is 31% on average, highest around October 15 (32%). In all, 3.18 in falls on 10 days of a normal October, 1 of them with an inch or more.
In a normal October in Decatur, 3 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00003887.
How humid and windy is Decatur in October?
At 3 p.m. the normal temperature is 56°F with 54% relative humidity and a dew point of 40°F; at 6 a.m. it is 43°F with 82% humidity. The wind averages 10.4 mph, most often from the west-southwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 43°F | 38°F | 82% | 9.2 mph | 57% |
| 9 a.m. | 49°F | 40°F | 71% | 11.9 mph | 55% |
| noon | 55°F | 40°F | 58% | 13.0 mph | 52% |
| 3 p.m. | 56°F | 40°F | 54% | 12.8 mph | 51% |
| 6 p.m. | 51°F | 39°F | 65% | 9.5 mph | 54% |
| 9 p.m. | 47°F | 39°F | 73% | 9.4 mph | 61% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00003887. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for October in Decatur?
The warmest October temperature on this station's record (since 2000) is 93°F, on October 8, 2007; the coldest is 23°F, on October 21, 2018. The wettest October brought 8.98 in (2009).
The October mean against the 1991-2020 normal of 55.2°F: 2021 60.2°F (+5.0), 2022 54.0°F (−1.2), 2023 56.6°F (+1.4), 2024 59.3°F (+4.1), 2025 59.0°F (+3.8). 4 of 5 ran warmer than normal.
| October | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 60.2°F | +5.0°F | 6.57 in |
| 2022 | 54.0°F | −1.2°F | 2.95 in |
| 2023 | 56.6°F | +1.4°F | 3.70 in |
| 2024 | 59.3°F | +4.1°F | 1.01 in |
| 2025 | 59.0°F | +3.8°F | 1.70 in |
Source: records: ACIS, station USW00003887; recent months: ACIS, station USW00003887. Records and recent months use complete months only.
How does October in Decatur compare across Illinois?
Across the 144 places PlainClimate covers in Illinois, October normal highs run from 60°F in Barrington to 73°F in Anna; Decatur's is 66°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.