Des Moines weather in September: Des Moines, Iowa: normal highs, lows, rain and records for September
Des Moines in September has a normal high of 77°F and a normal low of 55°F, a daily mean of 66°F, falling from 81°F on the 1st to 71°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 3.18 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 25°C and low of 13°C, 81 mm of precipitation in September.
- NOAA stationDes Moines International Airport
- Station IDUSW00014933
- Location41.53°N 93.65°W
- Elevation957 ft (292 m)
- From the center3 miles
- Population213,096
- Jan 31° 14°
- Feb 36° 18°
- Mar 49° 30°
- Apr 62° 41°
- May 72° 52°
- Jun 82° 62°
- Jul 86° 66°
- Aug 84° 64°
- Sep 77° 55°
- Oct 63° 43°
- Nov 48° 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 Des Moines in September?
The normal high is 77°F and the normal low 55°F, for a daily mean of 66.2°F. September is 7.7°F cooler than August and 13.0°F warmer than October. September is the 4th warmest month of the year in Des Moines and the 6th wettest. Across the month the normal high falls 10°F, from 81°F on September 1 to 71°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 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 28%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 81°F | 61°F | 28% | 18% |
| September 8 | 80°F | 58°F | 28% | 18% |
| September 15 | 77°F | 56°F | 28% | 17% |
| September 22 | 75°F | 53°F | 28% | 17% |
| September 30 | 71°F | 50°F | 28% | 16% |
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 | 81°F | 61°F | 28% | 18% | 13 h 10 min |
| September 2 | 81°F | 60°F | 28% | 18% | 13 h 10 min |
| September 3 | 81°F | 60°F | 28% | 18% | 13 h 10 min |
| September 4 | 81°F | 60°F | 28% | 18% | 13 h |
| September 5 | 80°F | 59°F | 28% | 18% | 13 h |
| September 6 | 80°F | 59°F | 28% | 18% | 13 h |
| September 7 | 80°F | 59°F | 28% | 18% | 12 h 50 min |
| September 8 | 80°F | 58°F | 28% | 18% | 12 h 50 min |
| September 9 | 79°F | 58°F | 28% | 18% | 12 h 50 min |
| September 10 | 79°F | 58°F | 28% | 18% | 12 h 50 min |
| September 11 | 79°F | 57°F | 28% | 18% | 12 h 40 min |
| September 12 | 78°F | 57°F | 28% | 17% | 12 h 40 min |
| September 13 | 78°F | 57°F | 28% | 17% | 12 h 40 min |
| September 14 | 78°F | 56°F | 28% | 17% | 12 h 40 min |
| September 15 | 77°F | 56°F | 28% | 17% | 12 h 30 min |
| September 16 | 77°F | 55°F | 28% | 17% | 12 h 30 min |
| September 17 | 77°F | 55°F | 28% | 17% | 12 h 30 min |
| September 18 | 76°F | 55°F | 28% | 17% | 12 h 20 min |
| September 19 | 76°F | 54°F | 28% | 17% | 12 h 20 min |
| September 20 | 76°F | 54°F | 28% | 17% | 12 h 20 min |
| September 21 | 75°F | 53°F | 28% | 17% | 12 h 20 min |
| September 22 | 75°F | 53°F | 28% | 17% | 12 h 10 min |
| September 23 | 75°F | 53°F | 28% | 17% | 12 h 10 min |
| September 24 | 74°F | 52°F | 28% | 17% | 12 h 10 min |
| September 25 | 74°F | 52°F | 28% | 17% | 12 h 10 min |
| September 26 | 73°F | 51°F | 28% | 17% | 12 h |
| September 27 | 73°F | 51°F | 28% | 17% | 12 h |
| September 28 | 72°F | 50°F | 28% | 16% | 12 h |
| September 29 | 72°F | 50°F | 28% | 16% | 11 h 50 min |
| September 30 | 71°F | 50°F | 28% | 16% | 11 h 50 min |
- Normal high
- 77°FSeptember average
- Normal low
- 55°FSeptember average
- Precipitation
- 3.18 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
- 13
- Sunshine
- 80%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014933; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Des Moines in September?
On a given September day the chance of 0.01 inch or more is 28% on average, highest around September 1 (28%). In all, 3.18 in falls on 8 days of a normal September, 1 of them with an inch or more.
In a normal September in Des Moines, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014933.
How humid and windy is Des Moines in September?
At 3 p.m. the normal temperature is 70°F with 46% relative humidity and a dew point of 48°F; at 6 a.m. it is 52°F with 81% humidity. The wind averages 9.0 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. | 52°F | 47°F | 81% | 7.4 mph | 49% |
| 9 a.m. | 59°F | 49°F | 70% | 9.8 mph | 54% |
| noon | 67°F | 49°F | 52% | 11.5 mph | 41% |
| 3 p.m. | 70°F | 48°F | 46% | 11.9 mph | 48% |
| 6 p.m. | 65°F | 48°F | 54% | 8.3 mph | 47% |
| 9 p.m. | 60°F | 48°F | 66% | 8.2 mph | 58% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014933. 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 Des Moines?
The warmest September temperature on Des Moines's official record (since 1878) is 101°F, on September 7, 1939; the coldest is 26°F, on September 30, 1899. The wettest September brought 14.81 in (1914).
The September mean against the 1991-2020 normal of 66.2°F: 2021 70.3°F (+4.1), 2022 67.8°F (+1.5), 2023 70.5°F (+4.3), 2024 70.9°F (+4.7), 2025 69.8°F (+3.6), 2026 70.6°F (+4.4). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 70.3°F | +4.1°F | 0.83 in |
| 2022 | 67.8°F | +1.5°F | 3.52 in |
| 2023 | 70.5°F | +4.3°F | 2.43 in |
| 2024 | 70.9°F | +4.7°F | 0.60 in |
| 2025 | 69.8°F | +3.6°F | 1.76 in |
| 2026 | 70.6°F | +4.4°F | 14.50 in |
Source: records: ACIS, NWS threaded record DSMthr; recent months: ACIS, station USW00014933. Records and recent months use complete months only.
How does September in Des Moines 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; Des Moines's is 77°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.