Indianapolis weather in September: Indianapolis, Indiana: normal highs, lows, rain and records for September
Indianapolis in September has a normal high of 78°F and a normal low of 57°F, a daily mean of 68°F, falling from 83°F on the 1st to 73°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 3.14 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 26°C and low of 14°C, 80 mm of precipitation in September.
- NOAA stationIndianapolis International Airport
- Station IDUSW00093819
- Location39.71°N 86.28°W
- Elevation790 ft (241 m)
- From the center9 miles
- Population891,484
- Jan 36° 21°
- Feb 41° 24°
- Mar 52° 33°
- Apr 64° 43°
- May 73° 54°
- Jun 82° 63°
- Jul 85° 66°
- Aug 84° 65°
- Sep 78° 57°
- Oct 66° 46°
- Nov 52° 35°
- Dec 40° 26°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Indianapolis in September?
The normal high is 78°F and the normal low 57°F, for a daily mean of 67.8°F. September is 6.9°F cooler than August and 12.3°F warmer than October. September is the 4th warmest month of the year in Indianapolis and the 9th wettest. Across the month the normal high falls 10°F, from 83°F on September 1 to 73°F on September 30. From one year to the next September's mean temperature typically moves about 2.9°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 65°F and 71°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 27%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 83°F | 63°F | 26% | 16% |
| September 8 | 81°F | 60°F | 26% | 16% |
| September 15 | 79°F | 58°F | 26% | 16% |
| September 22 | 76°F | 55°F | 27% | 17% |
| September 30 | 73°F | 52°F | 27% | 17% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 83°F | 63°F | 26% | 16% | 13 h 10 min |
| September 2 | 82°F | 62°F | 26% | 16% | 13 h |
| September 3 | 82°F | 62°F | 26% | 16% | 13 h |
| September 4 | 82°F | 62°F | 26% | 16% | 13 h |
| September 5 | 82°F | 61°F | 26% | 16% | 13 h |
| September 6 | 82°F | 61°F | 26% | 16% | 12 h 50 min |
| September 7 | 81°F | 61°F | 26% | 16% | 12 h 50 min |
| September 8 | 81°F | 60°F | 26% | 16% | 12 h 50 min |
| September 9 | 81°F | 60°F | 26% | 16% | 12 h 50 min |
| September 10 | 80°F | 60°F | 26% | 16% | 12 h 40 min |
| September 11 | 80°F | 59°F | 26% | 16% | 12 h 40 min |
| September 12 | 80°F | 59°F | 26% | 16% | 12 h 40 min |
| September 13 | 79°F | 59°F | 26% | 16% | 12 h 40 min |
| September 14 | 79°F | 58°F | 26% | 16% | 12 h 30 min |
| September 15 | 79°F | 58°F | 26% | 16% | 12 h 30 min |
| September 16 | 78°F | 57°F | 26% | 16% | 12 h 30 min |
| September 17 | 78°F | 57°F | 26% | 16% | 12 h 30 min |
| September 18 | 78°F | 57°F | 26% | 16% | 12 h 20 min |
| September 19 | 77°F | 56°F | 26% | 16% | 12 h 20 min |
| September 20 | 77°F | 56°F | 27% | 17% | 12 h 20 min |
| September 21 | 76°F | 55°F | 27% | 17% | 12 h 20 min |
| September 22 | 76°F | 55°F | 27% | 17% | 12 h 10 min |
| September 23 | 76°F | 55°F | 27% | 17% | 12 h 10 min |
| September 24 | 75°F | 54°F | 27% | 17% | 12 h 10 min |
| September 25 | 75°F | 54°F | 27% | 17% | 12 h 10 min |
| September 26 | 74°F | 53°F | 27% | 17% | 12 h |
| September 27 | 74°F | 53°F | 27% | 17% | 12 h |
| September 28 | 74°F | 52°F | 27% | 17% | 12 h |
| September 29 | 73°F | 52°F | 27% | 17% | 11 h 50 min |
| September 30 | 73°F | 52°F | 27% | 17% | 11 h 50 min |
- Normal high
- 78°FSeptember average
- Normal low
- 57°FSeptember average
- Precipitation
- 3.14 inmonth total
- Days with precipitation
- 80.01 inch or more
- Days at 90°F or more
- 3
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 25
- Days at 80°F or more
- 14
- Sunshine
- 80%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00093819; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Indianapolis in September?
On a given September day the chance of 0.01 inch or more is 26% on average, highest around September 30 (27%). In all, 3.14 in falls on 8 days of a normal September, 1 of them with an inch or more.
In a normal September in Indianapolis, 3 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00093819.
How humid and windy is Indianapolis in September?
At 3 p.m. the normal temperature is 71°F with 48% relative humidity and a dew point of 51°F; at 6 a.m. it is 54°F with 85% humidity. The wind averages 8.6 mph, most often from the west-southwest in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 54°F | 50°F | 85% | 7.0 mph | 58% |
| 9 a.m. | 59°F | 52°F | 76% | 8.4 mph | 47% |
| noon | 68°F | 52°F | 56% | 10.3 mph | 40% |
| 3 p.m. | 71°F | 51°F | 48% | 11.1 mph | 40% |
| 6 p.m. | 68°F | 50°F | 53% | 9.5 mph | 43% |
| 9 p.m. | 61°F | 51°F | 68% | 7.8 mph | 54% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00093819. 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 September in Indianapolis?
The warmest September temperature on Indianapolis's official record (since 1871) is 100°F, on September 15, 1939; the coldest is 30°F, on September 30, 1899. The wettest September brought 10.37 in (2003).
The September mean against the 1991-2020 normal of 67.8°F: 2021 70.2°F (+2.4), 2022 68.1°F (+0.3), 2023 69.8°F (+2.0), 2024 70.9°F (+3.1), 2025 70.5°F (+2.7), 2026 73.8°F (+6.0). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 70.2°F | +2.4°F | 5.25 in |
| 2022 | 68.1°F | +0.3°F | 2.12 in |
| 2023 | 69.8°F | +2.0°F | 1.60 in |
| 2024 | 70.9°F | +3.1°F | 1.52 in |
| 2025 | 70.5°F | +2.7°F | 1.77 in |
| 2026 | 73.8°F | +6.0°F | 1.29 in |
Source: records: ACIS, NWS threaded record INDthr; recent months: ACIS, station USW00093819. Records and recent months use complete months only.
How does September in Indianapolis compare across Indiana?
Across the 99 places PlainClimate covers in Indiana, September normal highs run from 74°F in Angola to 82°F in English; Indianapolis's is 78°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Indianapolis in August84°F by day, 65°F at night
- Indianapolis in October66°F by day, 46°F at night
- Indianapolis through the yearEvery month, frost dates, records and recent years
- Indiana in SeptemberThe statewide normal and the warmest and coolest places
- English: Indiana's warmest Septembernormal high 82°F