Indianapolis, IN weather in September
September in Indianapolis: mild, with some rain. Highs 78°F, lows 57°F, about 8 wet days. A good month for most outdoor plans.
- Normal high
- 78°F
- Normal low
- 57°F
- Wet days
- 8
- 3.1 in total
- Muggy days
- 5
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 83°F | 73°F |
| Normal low | 63°F | 52°F |
| Chance of a wet day | 26% | 27% |
| Sunrise / sunset | 7:12 am / 8:16 pm | 7:39 am / 7:29 pm |
| Daylight | 13.1 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am60°Fdew point 56°F
- 9 am65°Fdew point 57°F
- Noon74°Fdew point 57°F
- 3 pm77°Fdew point 56°F
- 6 pm74°Fdew point 56°F
- 9 pm67°Fdew point 56°F
NOAA hourly normals (local standard time) from Indianapolis (9 mi away); average wind 8 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F13 of 30
- Hot dayshigh 90°F or more3 of 30
- Muggy daysdaily mean dew point 65°F or more5 of 30
- Wet daysat least 0.01 in of rain or melted snow8 of 30
- Notable rainat least 0.10 in5 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 3.1 in; a dry September brings about 1.2 in and a wet one about 4.7 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202019: average high 84°F
- Coolest September1993: average high 72°F
- Wettest September2003: 10.4 in
- Driest September2020: 0.1 in
- Highest reading100°F (September 3, 2011)
- Lowest reading32°F (September 30, 1993)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 84°F | 78°F | 66°F |
| Normal low | 65°F | 57°F | 46°F |
| Wet days | 8 | 8 | 9 |
| Comfortable days | 4 | 13 | 13 |
| Daylight | 13.7 h | 12.4 h | 11.1 h |
Highs change by -6°F from August and -12°F into October.
Nearby alternatives in September
- Warmer: Clarksville, TN234 mi · high 84°F · 9 wet days
How Indianapolis ranks in September
- Normal high220th warmest of 378 cities; 2nd of 6 in Indiana
- Wet days192nd driest of 378
- Comfortable days125th most of 342
Heating and cooling
September has 58 heating degree days and 142 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Indianapolis in September?
The normal high is 78°F and the normal low is 57°F. From 1991 to 2020 the hottest September reading was 100°F (September 3, 2011).
Does it rain a lot in Indianapolis in September?
About 8 days in September have at least 0.01 in of precipitation, and the normal total is 3.1 in. The wettest September in 1991-2020 was in 2003 (10.4 in); the driest was in 2020 (0.1 in).
Is September a good time to visit Indianapolis?
September ranks 3rd of 12 months on our comfort score for Indianapolis (65 out of 100). It has about 13 comfortable days and about 3 days at 90°F or hotter. The best months are April and May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth, frost dates and humidity and wind by hour: Indianapolis (USW00093819), 8.6 mi SW of the city center, 790 ft (72 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Indianapolis International Airport (724380-93819), 8.1 mi WSW of the city center, 792 ft (74 ft higher than the city). Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).