August is one of the warmer months of the year in Waterloo, with average highs near 26.6°C and lows around 14.5°C (mean 20.6°C). It is about average for rainfall, averaging 66 mm of rainfall and 69% relative humidity across the period.
August is one of the warmer months of the year in Waterloo. Across 45 years of records, the warmest August in Waterloo was 2021 — when the month averaged 23.4°C — while the coldest was 1992 at 17.3°C. Typical August days reach 26.6°C with nights near 14.5°C. The long-term trend is warming, about 0.3°C per decade.
August is about average for rainfall in Waterloo, averaging 66 mm of rainfall. The wettest August on record was 1992 with 117 mm, while the driest was 2002 at 19 mm.
Relative humidity in Waterloo during August averages 69%. The most humid August was 2000 at 80%, and the least humid was 1987 at 60%.
August receives about 5.2 kWh/m²/day of solar energy in Waterloo. The sunniest Augusts were 2002 and 2019 at 5.8 kWh/m²/day, and the cloudiest was 1997 at 4.6.
Average wind speed in Waterloo during August is 2.5 m/s. The windiest August was 1987 at 3.2 m/s, while the calmest were 1998, 2003 and 2021, among others at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.2°C | 20.2°C | 20.4°C | 20.8°C | 21.4°C | +1.2°C |
| Avg High | 26.4°C | 26.3°C | 26.5°C | 26.7°C | 27.5°C | +1.1°C |
| Avg Low | 14.0°C | 14.1°C | 14.4°C | 14.9°C | 15.3°C | +1.3°C |
| Avg Rain | 75 mm | 68 mm | 58 mm | 67 mm | 65 mm | -10 mm |
August temperatures in Waterloo have risen by about 1.4°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 2.9°C (1982) to a record high of 36.5°C (2001).
Rainfall in August is about average for rainfall, averaging 66 mm, with a wettest year of 117 mm.
One of the best times to visit Waterloo
August is one of the best times to visit Waterloo. Expect days averaging 26.6°C and nights around 14.5°C (mean 20.6°C) — warmer than Waterloo's yearly average — with moderate rainfall (66 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 27.5°C | 21.0°C | 14.5°C | 34.3°C | 6.4°C | 44 mm | 63% | 2.3 m/s | 5.4 |
| 2024 | 27.5°C | 21.4°C | 15.3°C | 33.8°C | 8.0°C | 67 mm | 67% | 2.4 m/s | 5 |
| 2023 | 25.4°C | 19.5°C | 13.6°C | 29.7°C | 7.8°C | 83 mm | 71% | 2.7 m/s | 5 |
| 2022 | 27.8°C | 21.5°C | 15.2°C | 32.9°C | 10.9°C | 62 mm | 67% | 2.5 m/s | 5.3 |
| 2021 🔥 | 29.4°C | 23.4°C | 17.5°C | 34.3°C | 11.1°C | 50 mm | 67% | 2.2 m/s | 5.4 |
| 2020 | 27.6°C | 21.6°C | 15.6°C | 32.5°C | 11.2°C | 83 mm | 70% | 2.7 m/s | 5.5 |
| 2019 | 27.1°C | 20.9°C | 14.7°C | 31.4°C | 9.0°C | 50 mm | 67% | 2.6 m/s | 5.8 |
| 2018 | 27.3°C | 22.1°C | 16.9°C | 33.2°C | 12.2°C | 107 mm | 76% | 2.5 m/s | 4.9 |
| 2017 | 24.2°C | 18.8°C | 13.4°C | 30.0°C | 8.0°C | 49 mm | 74% | 2.5 m/s | 5.1 |
| 2016 | 29.3°C | 23.1°C | 16.9°C | 34.3°C | 11.9°C | 88 mm | 69% | 2.5 m/s | 5.7 |
| 2015 | 25.9°C | 20.0°C | 14.1°C | 32.4°C | 10.0°C | 67 mm | 71% | 2.5 m/s | 5.2 |
| 2014 | 25.0°C | 19.3°C | 13.5°C | 30.5°C | 9.6°C | 55 mm | 75% | 2.5 m/s | 5.2 |
| 2013 | 25.3°C | 19.5°C | 13.8°C | 30.6°C | 8.8°C | 68 mm | 73% | 2.3 m/s | 5.5 |
| 2012 | 26.5°C | 20.5°C | 14.4°C | 33.0°C | 8.6°C | 80 mm | 69% | 2.3 m/s | 5.5 |
| 2011 | 27.7°C | 21.6°C | 15.6°C | 31.9°C | 11.5°C | 73 mm | 66% | 2.4 m/s | 5.3 |
| 2010 | 28.4°C | 22.2°C | 16.1°C | 33.7°C | 9.6°C | 32 mm | 69% | 2.5 m/s | 5.2 |
| 2009 | 25.5°C | 19.9°C | 14.4°C | 31.1°C | 7.4°C | 97 mm | 73% | 2.6 m/s | 5.1 |
| 2008 | 24.9°C | 19.0°C | 13.1°C | 30.1°C | 8.2°C | 77 mm | 72% | 2.4 m/s | 5.6 |
| 2007 | 28.3°C | 21.8°C | 15.2°C | 35.3°C | 8.2°C | 34 mm | 64% | 2.7 m/s | 5.1 |
| 2006 | 27.1°C | 20.9°C | 14.6°C | 35.4°C | 9.0°C | 34 mm | 66% | 2.6 m/s | 5.5 |
| 2005 | 27.9°C | 21.6°C | 15.4°C | 32.4°C | 9.9°C | 65 mm | 68% | 2.6 m/s | 5.2 |
| 2004 | 24.0°C | 18.4°C | 12.9°C | 27.9°C | 7.1°C | 50 mm | 73% | 2.7 m/s | 4.9 |
| 2003 | 26.5°C | 20.9°C | 15.2°C | 31.5°C | 9.7°C | 74 mm | 72% | 2.2 m/s | 5.3 |
| 2002 | 28.4°C | 21.6°C | 14.8°C | 33.8°C | 10.5°C | 19 mm | 63% | 2.7 m/s | 5.8 |
| 2001 | 28.4°C | 21.9°C | 15.4°C | 36.5°C | 10.5°C | 66 mm | 65% | 2.6 m/s | 5.4 |
| 2000 | 23.5°C | 18.4°C | 13.2°C | 28.1°C | 5.8°C | 69 mm | 80% | 2.4 m/s | 5 |
| 1999 | 25.5°C | 19.5°C | 13.6°C | 30.5°C | 8.0°C | 56 mm | 67% | 2.7 m/s | 5 |
| 1998 | 27.9°C | 21.6°C | 15.3°C | 32.4°C | 8.0°C | 49 mm | 65% | 2.2 m/s | 5.4 |
| 1997 | 24.4°C | 18.5°C | 12.5°C | 30.2°C | 8.7°C | 80 mm | 70% | 2.7 m/s | 4.6 |
| 1996 | 27.5°C | 20.8°C | 14.1°C | 32.5°C | 9.7°C | 32 mm | 66% | 2.2 m/s | 5.6 |
| 1995 | 28.6°C | 22.4°C | 16.3°C | 32.6°C | 8.6°C | 77 mm | 67% | 2.5 m/s | 5.1 |
| 1994 | 24.9°C | 18.8°C | 12.7°C | 29.1°C | 8.3°C | 69 mm | 71% | 2.6 m/s | 5.1 |
| 1993 | 27.9°C | 21.6°C | 15.4°C | 32.9°C | 10.0°C | 44 mm | 65% | 2.3 m/s | 5.6 |
| 1992 ❄️ 🌧️ | 23.1°C | 17.3°C | 11.5°C | 28.9°C | 7.0°C | 117 mm | 76% | 2.8 m/s | 4.9 |
| 1991 | 26.8°C | 20.9°C | 15.1°C | 33.1°C | 9.3°C | 75 mm | 69% | 2.6 m/s | 5.3 |
| 1990 | 26.5°C | 20.4°C | 14.2°C | 30.6°C | 10.0°C | 79 mm | 70% | 2.4 m/s | 4.9 |
| 1989 | 27.3°C | 20.7°C | 14.2°C | 32.9°C | 9.1°C | 35 mm | 63% | 2.8 m/s | 4.9 |
| 1988 | 27.6°C | 21.5°C | 15.5°C | 33.5°C | 9.1°C | 76 mm | 67% | 2.8 m/s | 5.3 |
| 1987 | 27.3°C | 21.0°C | 14.8°C | 34.0°C | 8.8°C | 45 mm | 60% | 3.2 m/s | 4.9 |
| 1986 | 24.4°C | 18.7°C | 12.9°C | 31.0°C | 4.9°C | 86 mm | 69% | 2.7 m/s | 5.3 |
| 1985 | 25.7°C | 19.4°C | 13.1°C | 31.9°C | 7.8°C | 113 mm | 67% | 2.6 m/s | 5.1 |
| 1984 | 27.7°C | 21.3°C | 14.9°C | 31.6°C | 8.2°C | 57 mm | 68% | 2.4 m/s | 5.5 |
| 1983 | 27.6°C | 21.4°C | 15.2°C | 32.6°C | 9.0°C | 71 mm | 69% | 2.3 m/s | — |
| 1982 | 23.9°C | 17.8°C | 11.7°C | 29.9°C | 2.9°C | 96 mm | 71% | 2.6 m/s | — |
| 1981 | 25.8°C | 20.0°C | 14.1°C | 30.1°C | 7.6°C | 93 mm | 69% | 2.4 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 26.6°C with lows near 14.5°C (mean 20.6°C), based on 45 years of NASA POWER data.
August averages 66 mm of rainfall in Waterloo, about average for rainfall. The wettest on record was 117 mm in 1992.
The hottest August reached 36.5°C in 2001. The coldest dipped to 2.9°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.4°C. Daytime highs moved from 26.1°C to 27.5°C and overnight lows from 13.8°C to 15.2°C over the same span.
August is one of the warmer months of the year in Waterloo and about average for rainfall, so plan for around 26.6°C daytime highs and 14.5°C at night.
Not quite — August is the 11th coolest month in Waterloo, averaging 20.6°C.
For August in Waterloo, pack light layers you can adjust through the day, with typical highs of 26.6°C and lows of 14.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 69% — moderately humid.
Average wind speed in August is 2.5 m/s. The windiest August on record averaged 3.2 m/s (1987).
The wettest August on record was 1992 with 117 mm. On average, August sees 66 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Waterloo behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
