Ottumwa weather in August: Ottumwa, Iowa: normal highs, lows, rain and records for August
Ottumwa in August has a normal high of 84°F and a normal low of 62°F, a daily mean of 73°F, falling from 85°F on the 1st to 82°F by the 31st. Measurable precipitation falls on 9 days in a normal August, 4.44 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 29°C and low of 17°C, 113 mm of precipitation in August.
- 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 August?
The normal high is 84°F and the normal low 62°F, for a daily mean of 73.0°F. August is 2.1°F cooler than July and 7.7°F warmer than September. August is the 2nd warmest month of the year in Ottumwa and the 3rd wettest. Across the month the normal high falls 3°F, from 85°F on August 1 to 82°F on August 31. From one year to the next August's mean temperature typically moves about 2.4°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 71°F and 75°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 30%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 85°F | 64°F | 30% | 21% |
| August 8 | 85°F | 64°F | 30% | 20% |
| August 15 | 84°F | 63°F | 29% | 20% |
| August 22 | 83°F | 61°F | 29% | 20% |
| August 31 | 82°F | 59°F | 29% | 20% |
Every day of August: normal high, low and chance of precipitation (warmest afternoon August 1, coldest night August 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| August 1 | 85°F | 64°F | 30% | 21% | 14 h 20 min |
| August 2 | 85°F | 64°F | 30% | 21% | 14 h 20 min |
| August 3 | 85°F | 64°F | 30% | 21% | 14 h 20 min |
| August 4 | 85°F | 64°F | 30% | 21% | 14 h 20 min |
| August 5 | 85°F | 64°F | 30% | 21% | 14 h 10 min |
| August 6 | 85°F | 64°F | 30% | 20% | 14 h 10 min |
| August 7 | 85°F | 64°F | 30% | 20% | 14 h 10 min |
| August 8 | 85°F | 64°F | 30% | 20% | 14 h 10 min |
| August 9 | 85°F | 63°F | 30% | 20% | 14 h 10 min |
| August 10 | 85°F | 63°F | 30% | 20% | 14 h |
| August 11 | 85°F | 63°F | 30% | 20% | 14 h |
| August 12 | 85°F | 63°F | 30% | 20% | 14 h |
| August 13 | 85°F | 63°F | 29% | 20% | 14 h |
| August 14 | 84°F | 63°F | 29% | 20% | 13 h 50 min |
| August 15 | 84°F | 63°F | 29% | 20% | 13 h 50 min |
| August 16 | 84°F | 62°F | 29% | 20% | 13 h 50 min |
| August 17 | 84°F | 62°F | 29% | 20% | 13 h 50 min |
| August 18 | 84°F | 62°F | 29% | 20% | 13 h 40 min |
| August 19 | 84°F | 62°F | 29% | 20% | 13 h 40 min |
| August 20 | 84°F | 62°F | 29% | 20% | 13 h 40 min |
| August 21 | 84°F | 61°F | 29% | 20% | 13 h 40 min |
| August 22 | 83°F | 61°F | 29% | 20% | 13 h 40 min |
| August 23 | 83°F | 61°F | 29% | 20% | 13 h 30 min |
| August 24 | 83°F | 61°F | 29% | 20% | 13 h 30 min |
| August 25 | 83°F | 60°F | 29% | 20% | 13 h 30 min |
| August 26 | 83°F | 60°F | 29% | 20% | 13 h 20 min |
| August 27 | 83°F | 60°F | 29% | 20% | 13 h 20 min |
| August 28 | 83°F | 60°F | 29% | 20% | 13 h 20 min |
| August 29 | 82°F | 59°F | 29% | 20% | 13 h 20 min |
| August 30 | 82°F | 59°F | 29% | 20% | 13 h 10 min |
| August 31 | 82°F | 59°F | 29% | 20% | 13 h 10 min |
- Normal high
- 84°FAugust average
- Normal low
- 62°FAugust average
- Precipitation
- 4.44 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 5
- Daylight
- 14 h 20 min to 13 h 10 minAugust 1 to August 31
- Days at 70°F or more
- 30
- Days at 80°F or more
- 23
- Sunshine
- 80%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 August?
On a given August day the chance of 0.01 inch or more is 29% on average, highest around August 2 (30%). In all, 4.44 in falls on 9 days of a normal August, 1 of them with an inch or more.
In a normal August in Ottumwa, 5 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014950.
How humid and windy is Ottumwa in August?
At 3 p.m. the normal temperature is 81°F with 52% relative humidity and a dew point of 62°F; at 6 a.m. it is 63°F with 91% humidity. The wind averages 7.9 mph, most often from the south-southeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 63°F | 60°F | 91% | 6.8 mph | 70% |
| 9 a.m. | 72°F | 63°F | 74% | 8.5 mph | 72% |
| noon | 79°F | 62°F | 58% | 9.5 mph | 69% |
| 3 p.m. | 81°F | 62°F | 52% | 10.0 mph | 65% |
| 6 p.m. | 77°F | 63°F | 63% | 7.4 mph | 74% |
| 9 p.m. | 69°F | 62°F | 79% | 7.3 mph | 79% |
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 August in Ottumwa?
The warmest August temperature on this station's record (since 1948) is 105°F, on August 18, 1983; the coldest is 41°F, on August 20, 1950. The wettest August brought 12.52 in (2010).
The August mean against the 1991-2020 normal of 73.0°F: 2021 74.2°F (+1.2), 2022 74.6°F (+1.6), 2023 73.6°F (+0.6), 2024 71.6°F (−1.4), 2025 71.6°F (−1.4), 2026 74.5°F (+1.5). 4 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 74.2°F | +1.2°F | 0.74 in |
| 2022 | 74.6°F | +1.6°F | 1.14 in |
| 2023 | 73.6°F | +0.6°F | 1.20 in |
| 2024 | 71.6°F | −1.4°F | 2.00 in |
| 2025 | 71.6°F | −1.4°F | 2.16 in |
| 2026 | 74.5°F | +1.5°F | 5.51 in |
Source: records: ACIS, station USW00014950; recent months: ACIS, station USW00014950. Records and recent months use complete months only.
How does August in Ottumwa compare across Iowa?
Across the 132 places PlainClimate covers in Iowa, August normal highs run from 76°F in Northwood to 85°F in Donnellson; Ottumwa's is 84°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.