Iowa City weather in September: Iowa City, Iowa: normal highs, lows, rain and records for September
Iowa City in September has a normal high of 78°F and a normal low of 54°F, a daily mean of 66°F, falling from 82°F on the 1st to 72°F by the 30th. Measurable precipitation falls on 10 days in a normal September, 3.24 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 25°C and low of 12°C, 82 mm of precipitation in September.
- NOAA stationIowa City Municipal Airport
- Station IDUSW00014937
- Location41.63°N 91.54°W
- Elevation650 ft (198 m)
- From the center2 miles
- Population76,710
- Jan 31° 15°
- Feb 36° 19°
- Mar 50° 30°
- Apr 63° 40°
- May 73° 52°
- Jun 83° 62°
- Jul 86° 66°
- Aug 84° 63°
- Sep 78° 54°
- Oct 64° 42°
- Nov 49° 30°
- Dec 36° 20°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Iowa City in September?
The normal high is 78°F and the normal low 54°F, for a daily mean of 65.8°F. September is 7.7°F cooler than August and 12.7°F warmer than October. September is the 4th warmest month of the year in Iowa City and the 6th wettest. Across the month the normal high falls 10°F, from 82°F on September 1 to 72°F on September 30. From one year to the next September's mean temperature typically moves about 3.0°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 63°F and 69°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 33%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 82°F | 60°F | 33% | 19% |
| September 8 | 80°F | 57°F | 33% | 18% |
| September 15 | 78°F | 55°F | 33% | 18% |
| September 22 | 76°F | 52°F | 33% | 17% |
| September 30 | 72°F | 48°F | 32% | 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 | 82°F | 60°F | 33% | 19% | 13 h 10 min |
| September 2 | 81°F | 59°F | 33% | 19% | 13 h 10 min |
| September 3 | 81°F | 59°F | 33% | 18% | 13 h 10 min |
| September 4 | 81°F | 59°F | 33% | 18% | 13 h |
| September 5 | 81°F | 58°F | 33% | 18% | 13 h |
| September 6 | 81°F | 58°F | 33% | 18% | 13 h |
| September 7 | 80°F | 58°F | 33% | 18% | 12 h 50 min |
| September 8 | 80°F | 57°F | 33% | 18% | 12 h 50 min |
| September 9 | 80°F | 57°F | 33% | 18% | 12 h 50 min |
| September 10 | 80°F | 56°F | 33% | 18% | 12 h 50 min |
| September 11 | 79°F | 56°F | 33% | 18% | 12 h 40 min |
| September 12 | 79°F | 56°F | 33% | 18% | 12 h 40 min |
| September 13 | 79°F | 55°F | 33% | 18% | 12 h 40 min |
| September 14 | 78°F | 55°F | 33% | 18% | 12 h 40 min |
| September 15 | 78°F | 55°F | 33% | 18% | 12 h 30 min |
| September 16 | 78°F | 54°F | 33% | 18% | 12 h 30 min |
| September 17 | 77°F | 54°F | 33% | 18% | 12 h 30 min |
| September 18 | 77°F | 53°F | 33% | 18% | 12 h 20 min |
| September 19 | 77°F | 53°F | 33% | 18% | 12 h 20 min |
| September 20 | 76°F | 53°F | 33% | 18% | 12 h 20 min |
| September 21 | 76°F | 52°F | 33% | 18% | 12 h 20 min |
| September 22 | 76°F | 52°F | 33% | 17% | 12 h 10 min |
| September 23 | 75°F | 51°F | 33% | 17% | 12 h 10 min |
| September 24 | 75°F | 51°F | 33% | 17% | 12 h 10 min |
| September 25 | 74°F | 51°F | 33% | 17% | 12 h 10 min |
| September 26 | 74°F | 50°F | 32% | 17% | 12 h |
| September 27 | 73°F | 50°F | 32% | 17% | 12 h |
| September 28 | 73°F | 49°F | 32% | 17% | 12 h |
| September 29 | 73°F | 49°F | 32% | 17% | 11 h 50 min |
| September 30 | 72°F | 48°F | 32% | 17% | 11 h 50 min |
- Normal high
- 78°FSeptember average
- Normal low
- 54°FSeptember average
- Precipitation
- 3.24 inmonth total
- Days with precipitation
- 100.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 24
- Days at 80°F or more
- 13
- Sunshine
- 81%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014937; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Iowa City in September?
On a given September day the chance of 0.01 inch or more is 33% on average, highest around September 10 (33%). In all, 3.24 in falls on 10 days of a normal September, 1 of them with an inch or more.
In a normal September in Iowa City, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014937.
What are the records for September in Iowa City?
The warmest September temperature on this station's record (since 1948) is 101°F, on September 9, 2013; the coldest is 26°F, on September 23, 1995. The wettest September brought 11.35 in (2026).
The September mean against the 1991-2020 normal of 65.8°F: 2021 69.2°F (+3.4), 2022 67.3°F (+1.5), 2023 69.3°F (+3.5), 2024 68.7°F (+2.9), 2026 70.3°F (+4.5). 5 of 5 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 69.2°F | +3.4°F | 1.26 in |
| 2022 | 67.3°F | +1.5°F | 1.93 in |
| 2023 | 69.3°F | +3.5°F | 2.45 in |
| 2024 | 68.7°F | +2.9°F | 0.03 in |
| 2026 | 70.3°F | +4.5°F | 11.35 in |
Source: records: ACIS, station USW00014937; recent months: ACIS, station USW00014937. Records and recent months use complete months only.
How does September in Iowa City compare across Iowa?
Across the 132 places PlainClimate covers in Iowa, September normal highs run from 71°F in Northwood to 79°F in Glenwood; Iowa City's is 78°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.