Waterloo weather in August: Waterloo, Iowa: normal highs, lows, rain and records for August
Waterloo in August has a normal high of 83°F and a normal low of 61°F, a daily mean of 72°F, falling from 84°F on the 1st to 81°F by the 31st. Measurable precipitation falls on 9 days in a normal August, 4.17 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 28°C and low of 16°C, 106 mm of precipitation in August.
- NOAA stationWaterloo Municipal Airport
- Station IDUSW00094910
- Location42.55°N 92.40°W
- Elevation868 ft (265 m)
- Population67,477
- Jan 28° 11°
- Feb 33° 15°
- Mar 47° 27°
- Apr 61° 38°
- May 73° 50°
- Jun 82° 61°
- Jul 85° 64°
- Aug 83° 61°
- Sep 77° 52°
- Oct 63° 40°
- Nov 47° 28°
- Dec 34° 17°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Waterloo in August?
The normal high is 83°F and the normal low 61°F, for a daily mean of 71.9°F. August is 2.6°F cooler than July and 7.3°F warmer than September. August is the 2nd warmest month of the year in Waterloo and the 4th wettest. Across the month the normal high falls 3°F, from 84°F on August 1 to 81°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 70°F and 74°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 |
|---|---|---|---|---|
| August 1 | 84°F | 63°F | 28% | 19% |
| August 8 | 84°F | 62°F | 28% | 19% |
| August 15 | 83°F | 61°F | 28% | 18% |
| August 22 | 82°F | 60°F | 28% | 18% |
| August 31 | 81°F | 58°F | 29% | 18% |
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 | 84°F | 63°F | 28% | 19% | 14 h 30 min |
| August 2 | 84°F | 63°F | 28% | 19% | 14 h 30 min |
| August 3 | 84°F | 63°F | 28% | 19% | 14 h 30 min |
| August 4 | 84°F | 63°F | 28% | 19% | 14 h 20 min |
| August 5 | 84°F | 63°F | 28% | 19% | 14 h 20 min |
| August 6 | 84°F | 63°F | 28% | 19% | 14 h 20 min |
| August 7 | 84°F | 63°F | 28% | 19% | 14 h 20 min |
| August 8 | 84°F | 62°F | 28% | 19% | 14 h 10 min |
| August 9 | 84°F | 62°F | 28% | 19% | 14 h 10 min |
| August 10 | 84°F | 62°F | 28% | 19% | 14 h 10 min |
| August 11 | 84°F | 62°F | 28% | 19% | 14 h 10 min |
| August 12 | 83°F | 62°F | 28% | 19% | 14 h 10 min |
| August 13 | 83°F | 62°F | 28% | 19% | 14 h |
| August 14 | 83°F | 62°F | 28% | 18% | 14 h |
| August 15 | 83°F | 61°F | 28% | 18% | 14 h |
| August 16 | 83°F | 61°F | 28% | 18% | 14 h |
| August 17 | 83°F | 61°F | 28% | 18% | 13 h 50 min |
| August 18 | 83°F | 61°F | 28% | 18% | 13 h 50 min |
| August 19 | 83°F | 61°F | 28% | 18% | 13 h 50 min |
| August 20 | 83°F | 61°F | 28% | 18% | 13 h 50 min |
| August 21 | 83°F | 60°F | 28% | 18% | 13 h 40 min |
| August 22 | 82°F | 60°F | 28% | 18% | 13 h 40 min |
| August 23 | 82°F | 60°F | 28% | 18% | 13 h 40 min |
| August 24 | 82°F | 60°F | 28% | 18% | 13 h 30 min |
| August 25 | 82°F | 60°F | 29% | 18% | 13 h 30 min |
| August 26 | 82°F | 59°F | 29% | 18% | 13 h 30 min |
| August 27 | 82°F | 59°F | 29% | 18% | 13 h 30 min |
| August 28 | 82°F | 59°F | 29% | 18% | 13 h 20 min |
| August 29 | 81°F | 58°F | 29% | 18% | 13 h 20 min |
| August 30 | 81°F | 58°F | 29% | 18% | 13 h 20 min |
| August 31 | 81°F | 58°F | 29% | 18% | 13 h 20 min |
- Normal high
- 83°FAugust average
- Normal low
- 61°FAugust average
- Precipitation
- 4.17 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 3
- Daylight
- 14 h 30 min to 13 h 20 minAugust 1 to August 31
- Days at 70°F or more
- 30
- Days at 80°F or more
- 20
- Sunshine
- 80%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094910; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Waterloo in August?
On a given August day the chance of 0.01 inch or more is 28% on average, highest around August 28 (29%). In all, 4.17 in falls on 9 days of a normal August, 1 of them with an inch or more.
In a normal August in Waterloo, 3 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094910.
How humid and windy is Waterloo in August?
At 3 p.m. the normal temperature is 79°F with 54% relative humidity and a dew point of 61°F; at 6 a.m. it is 61°F with 91% humidity. The wind averages 7.4 mph, most often from the south in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 61°F | 58°F | 91% | 5.1 mph | 62% |
| 9 a.m. | 71°F | 61°F | 73% | 8.2 mph | 74% |
| noon | 78°F | 61°F | 57% | 10.5 mph | 62% |
| 3 p.m. | 79°F | 61°F | 54% | 11.1 mph | 68% |
| 6 p.m. | 75°F | 62°F | 63% | 7.9 mph | 73% |
| 9 p.m. | 67°F | 61°F | 82% | 5.9 mph | 79% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094910. 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 Waterloo?
The warmest August temperature on Waterloo's official record (since 1895) is 110°F, on August 18, 1936; the coldest is 33°F, on August 20, 1950. The wettest August brought 10.53 in (1998).
The August mean against the 1991-2020 normal of 71.9°F: 2021 74.0°F (+2.1), 2022 73.0°F (+1.1), 2023 74.8°F (+2.9), 2024 73.0°F (+1.0), 2025 70.7°F (−1.2), 2026 71.7°F (−0.2). 4 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 74.0°F | +2.1°F | 6.69 in |
| 2022 | 73.0°F | +1.1°F | 5.45 in |
| 2023 | 74.8°F | +2.9°F | 1.12 in |
| 2024 | 73.0°F | +1.0°F | 1.78 in |
| 2025 | 70.7°F | −1.2°F | 3.09 in |
| 2026 | 71.7°F | −0.2°F | 3.60 in |
Source: records: ACIS, NWS threaded record ALOthr; recent months: ACIS, station USW00094910. Records and recent months use complete months only.
How does August in Waterloo 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; Waterloo's is 83°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.