Ottumwa weather in September: Ottumwa, Iowa: normal highs, lows, rain and records for September
Ottumwa in September has a normal high of 77°F and a normal low of 53°F, a daily mean of 65°F, falling from 82°F on the 1st to 72°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 3.50 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 25°C and low of 12°C, 89 mm of precipitation in September.
- NOAA stationOttumwa Industrial Airport
- Station IDUSW00014950
- Location41.11°N 92.45°W
- Elevation842 ft (257 m)
- From the center6 miles
- Population25,648
- Jan 32° 14°
- Feb 37° 18°
- Mar 50° 29°
- Apr 63° 39°
- May 73° 51°
- Jun 82° 61°
- Jul 86° 65°
- Aug 84° 62°
- Sep 77° 53°
- Oct 64° 42°
- Nov 50° 30°
- Dec 37° 20°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Ottumwa in September?
The normal high is 77°F and the normal low 53°F, for a daily mean of 65.3°F. September is 7.7°F cooler than August and 12.4°F warmer than October. September is the 4th warmest month of the year in Ottumwa 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 3.1°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 62°F and 68°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 29%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 82°F | 58°F | 29% | 19% |
| September 8 | 80°F | 56°F | 28% | 19% |
| September 15 | 78°F | 54°F | 27% | 19% |
| September 22 | 75°F | 51°F | 27% | 18% |
| September 30 | 72°F | 48°F | 27% | 18% |
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 | 58°F | 29% | 19% | 13 h 10 min |
| September 2 | 82°F | 58°F | 28% | 19% | 13 h 10 min |
| September 3 | 81°F | 58°F | 28% | 19% | 13 h |
| September 4 | 81°F | 57°F | 28% | 19% | 13 h |
| September 5 | 81°F | 57°F | 28% | 19% | 13 h |
| September 6 | 81°F | 57°F | 28% | 19% | 13 h |
| September 7 | 80°F | 56°F | 28% | 19% | 12 h 50 min |
| September 8 | 80°F | 56°F | 28% | 19% | 12 h 50 min |
| September 9 | 80°F | 56°F | 28% | 19% | 12 h 50 min |
| September 10 | 79°F | 55°F | 28% | 19% | 12 h 50 min |
| September 11 | 79°F | 55°F | 28% | 19% | 12 h 40 min |
| September 12 | 79°F | 55°F | 28% | 19% | 12 h 40 min |
| September 13 | 79°F | 54°F | 28% | 19% | 12 h 40 min |
| September 14 | 78°F | 54°F | 28% | 19% | 12 h 30 min |
| September 15 | 78°F | 54°F | 27% | 19% | 12 h 30 min |
| September 16 | 78°F | 53°F | 27% | 19% | 12 h 30 min |
| September 17 | 77°F | 53°F | 27% | 19% | 12 h 30 min |
| September 18 | 77°F | 53°F | 27% | 19% | 12 h 20 min |
| September 19 | 76°F | 52°F | 27% | 19% | 12 h 20 min |
| September 20 | 76°F | 52°F | 27% | 19% | 12 h 20 min |
| September 21 | 76°F | 51°F | 27% | 19% | 12 h 20 min |
| September 22 | 75°F | 51°F | 27% | 18% | 12 h 10 min |
| September 23 | 75°F | 51°F | 27% | 18% | 12 h 10 min |
| September 24 | 74°F | 50°F | 27% | 18% | 12 h 10 min |
| September 25 | 74°F | 50°F | 27% | 18% | 12 h 10 min |
| September 26 | 74°F | 49°F | 27% | 18% | 12 h |
| September 27 | 73°F | 49°F | 27% | 18% | 12 h |
| September 28 | 73°F | 49°F | 27% | 18% | 12 h |
| September 29 | 72°F | 48°F | 27% | 18% | 11 h 50 min |
| September 30 | 72°F | 48°F | 27% | 18% | 11 h 50 min |
- Normal high
- 77°FSeptember average
- Normal low
- 53°FSeptember average
- Precipitation
- 3.50 inmonth total
- Days with precipitation
- 80.01 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
- 12
- Sunshine
- 81%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014950; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Ottumwa in September?
On a given September day the chance of 0.01 inch or more is 27% on average, highest around September 1 (29%). In all, 3.50 in falls on 8 days of a normal September, 1 of them with an inch or more.
In a normal September in Ottumwa, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014950.
How humid and windy is Ottumwa in September?
At 3 p.m. the normal temperature is 69°F with 48% relative humidity and a dew point of 49°F; at 6 a.m. it is 51°F with 86% humidity. The wind averages 9.6 mph, most often from the 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. | 51°F | 47°F | 86% | 8.0 mph | 71% |
| 9 a.m. | 59°F | 50°F | 70% | 10.5 mph | 70% |
| noon | 67°F | 49°F | 53% | 11.7 mph | 65% |
| 3 p.m. | 69°F | 49°F | 48% | 12.1 mph | 67% |
| 6 p.m. | 64°F | 49°F | 60% | 8.4 mph | 73% |
| 9 p.m. | 58°F | 49°F | 73% | 8.7 mph | 77% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014950. 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 Ottumwa?
The warmest September temperature on this station's record (since 1948) is 100°F, on September 1, 1984; the coldest is 27°F, on September 29, 1984. The wettest September brought 13.66 in (1965).
The September mean against the 1991-2020 normal of 65.3°F: 2021 69.1°F (+3.8), 2022 66.5°F (+1.2), 2023 68.4°F (+3.1), 2024 67.1°F (+1.8), 2025 68.6°F (+3.3), 2026 70.3°F (+5.0). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 69.1°F | +3.8°F | 1.03 in |
| 2022 | 66.5°F | +1.2°F | 4.17 in |
| 2023 | 68.4°F | +3.1°F | 1.19 in |
| 2024 | 67.1°F | +1.8°F | 0.71 in |
| 2025 | 68.6°F | +3.3°F | 0.83 in |
| 2026 | 70.3°F | +5.0°F | 7.59 in |
Source: records: ACIS, station USW00014950; recent months: ACIS, station USW00014950. Records and recent months use complete months only.
How does September in Ottumwa 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; Ottumwa's is 77°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.