August is one of the warmer months of the year in Guelph, with average highs near 27.5°C and lows around 15.2°C (mean 21.4°C). It is about average for rainfall, averaging 66 mm of rainfall and 66% relative humidity across the period.
August is one of the warmer months of the year in Guelph. Across 45 years of records, the warmest August in Guelph was 2021 — when the month averaged 24.2°C — while the coldest was 1992 at 18.1°C. Typical August days reach 27.5°C with nights near 15.2°C. The long-term trend is warming, about 0.3°C per decade.
August is about average for rainfall in Guelph, averaging 66 mm of rainfall. The wettest August on record was 1992 with 116 mm, while the driest was 2002 at 21 mm.
Relative humidity in Guelph during August averages 66%. The most humid August was 2000 at 76%, and the least humid was 1987 at 59%.
August receives about 5.2 kWh/m²/day of solar energy in Guelph. 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 Guelph during August is 2.4 m/s. The windiest August was 1987 at 3 m/s, while the calmest was 2003 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 21.0°C | 21.0°C | 21.3°C | 21.6°C | 22.2°C | +1.2°C |
| Avg High | 27.2°C | 27.1°C | 27.3°C | 27.6°C | 28.4°C | +1.2°C |
| Avg Low | 14.7°C | 14.8°C | 15.2°C | 15.7°C | 16.1°C | +1.4°C |
| Avg Rain | 74 mm | 66 mm | 60 mm | 65 mm | 63 mm | -11 mm |
August temperatures in Guelph 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 38.3°C (2001).
Rainfall in August is about average for rainfall, averaging 66 mm, with a wettest year of 116 mm.
One of the best times to visit Guelph
August is one of the best times to visit Guelph. Expect days averaging 27.5°C and nights around 15.2°C (mean 21.4°C) — warmer than Guelph'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 | 27.9°C | 21.6°C | 15.3°C | 34.9°C | 6.9°C | 45 mm | 61% | 2.2 m/s | 5.4 |
| 2024 | 28.1°C | 22.0°C | 15.9°C | 34.8°C | 8.9°C | 68 mm | 66% | 2.2 m/s | 5 |
| 2023 | 26.6°C | 20.5°C | 14.4°C | 31.3°C | 8.5°C | 81 mm | 68% | 2.5 m/s | 5 |
| 2022 | 28.7°C | 22.5°C | 16.2°C | 34.1°C | 11.9°C | 58 mm | 64% | 2.3 m/s | 5.3 |
| 2021 🔥 | 30.2°C | 24.2°C | 18.2°C | 35.1°C | 11.8°C | 47 mm | 65% | 2.2 m/s | 5.4 |
| 2020 | 28.7°C | 22.5°C | 16.3°C | 33.6°C | 11.7°C | 77 mm | 67% | 2.5 m/s | 5.5 |
| 2019 | 27.9°C | 21.6°C | 15.4°C | 32.8°C | 9.9°C | 53 mm | 65% | 2.4 m/s | 5.8 |
| 2018 | 28.3°C | 23.0°C | 17.8°C | 34.8°C | 12.8°C | 100 mm | 73% | 2.4 m/s | 4.9 |
| 2017 | 25.5°C | 19.8°C | 14.1°C | 31.7°C | 8.9°C | 49 mm | 70% | 2.4 m/s | 5.1 |
| 2016 | 30.4°C | 24.1°C | 17.9°C | 36.7°C | 12.2°C | 82 mm | 65% | 2.4 m/s | 5.7 |
| 2015 | 26.9°C | 20.9°C | 14.8°C | 33.3°C | 10.9°C | 65 mm | 68% | 2.4 m/s | 5.2 |
| 2014 | 25.8°C | 20.0°C | 14.2°C | 31.4°C | 9.9°C | 53 mm | 73% | 2.3 m/s | 5.2 |
| 2013 | 26.4°C | 20.5°C | 14.5°C | 31.1°C | 9.3°C | 69 mm | 69% | 2.2 m/s | 5.5 |
| 2012 | 27.7°C | 21.3°C | 15.0°C | 33.5°C | 9.7°C | 73 mm | 66% | 2.2 m/s | 5.5 |
| 2011 | 28.3°C | 22.2°C | 16.2°C | 33.4°C | 11.9°C | 73 mm | 64% | 2.3 m/s | 5.3 |
| 2010 | 28.9°C | 22.7°C | 16.6°C | 34.5°C | 9.2°C | 38 mm | 67% | 2.5 m/s | 5.2 |
| 2009 | 26.3°C | 20.8°C | 15.2°C | 32.0°C | 9.9°C | 104 mm | 71% | 2.4 m/s | 5.1 |
| 2008 | 25.4°C | 19.6°C | 13.7°C | 30.3°C | 9.6°C | 81 mm | 71% | 2.2 m/s | 5.6 |
| 2007 | 29.0°C | 22.5°C | 16.1°C | 36.3°C | 9.0°C | 34 mm | 61% | 2.6 m/s | 5.1 |
| 2006 | 27.7°C | 21.6°C | 15.4°C | 36.9°C | 10.2°C | 37 mm | 64% | 2.5 m/s | 5.5 |
| 2005 | 28.9°C | 22.6°C | 16.2°C | 34.1°C | 11.1°C | 69 mm | 65% | 2.5 m/s | 5.2 |
| 2004 | 24.9°C | 19.3°C | 13.7°C | 29.2°C | 8.2°C | 49 mm | 70% | 2.5 m/s | 4.9 |
| 2003 | 27.5°C | 21.7°C | 16.0°C | 32.1°C | 10.5°C | 69 mm | 70% | 2 m/s | 5.3 |
| 2002 | 29.3°C | 22.5°C | 15.8°C | 35.1°C | 11.7°C | 21 mm | 60% | 2.6 m/s | 5.8 |
| 2001 | 29.4°C | 22.9°C | 16.3°C | 38.3°C | 11.3°C | 65 mm | 61% | 2.4 m/s | 5.4 |
| 2000 | 24.9°C | 19.4°C | 14.0°C | 29.8°C | 6.8°C | 70 mm | 76% | 2.4 m/s | 5 |
| 1999 | 26.3°C | 20.4°C | 14.4°C | 32.3°C | 9.4°C | 55 mm | 64% | 2.6 m/s | 5 |
| 1998 | 28.5°C | 22.3°C | 16.0°C | 32.6°C | 9.2°C | 47 mm | 63% | 2.1 m/s | 5.4 |
| 1997 | 25.4°C | 19.4°C | 13.4°C | 30.8°C | 9.6°C | 78 mm | 67% | 2.5 m/s | 4.6 |
| 1996 | 28.3°C | 21.5°C | 14.7°C | 33.1°C | 10.6°C | 30 mm | 64% | 2.1 m/s | 5.6 |
| 1995 | 29.1°C | 22.9°C | 16.6°C | 34.5°C | 9.3°C | 73 mm | 66% | 2.3 m/s | 5.1 |
| 1994 | 26.0°C | 19.7°C | 13.5°C | 30.5°C | 8.7°C | 64 mm | 68% | 2.4 m/s | 5.1 |
| 1993 | 28.8°C | 22.4°C | 16.1°C | 34.2°C | 10.9°C | 43 mm | 62% | 2.1 m/s | 5.6 |
| 1992 ❄️ 🌧️ | 23.9°C | 18.1°C | 12.3°C | 29.7°C | 7.8°C | 116 mm | 73% | 2.7 m/s | 4.9 |
| 1991 | 27.6°C | 21.7°C | 15.7°C | 34.0°C | 10.3°C | 74 mm | 66% | 2.6 m/s | 5.3 |
| 1990 | 27.3°C | 21.2°C | 15.0°C | 31.2°C | 11.0°C | 78 mm | 67% | 2.3 m/s | 4.9 |
| 1989 | 28.0°C | 21.4°C | 14.7°C | 34.8°C | 8.9°C | 33 mm | 61% | 2.7 m/s | 4.9 |
| 1988 | 28.4°C | 22.3°C | 16.1°C | 34.4°C | 9.3°C | 71 mm | 64% | 2.7 m/s | 5.3 |
| 1987 | 27.8°C | 21.5°C | 15.2°C | 34.8°C | 9.4°C | 43 mm | 59% | 3 m/s | 4.9 |
| 1986 | 25.4°C | 19.5°C | 13.5°C | 32.1°C | 4.6°C | 88 mm | 67% | 2.5 m/s | 5.3 |
| 1985 | 26.6°C | 20.3°C | 14.0°C | 32.4°C | 8.9°C | 112 mm | 65% | 2.4 m/s | 5.1 |
| 1984 | 28.7°C | 22.3°C | 15.9°C | 33.4°C | 9.2°C | 53 mm | 64% | 2.3 m/s | 5.5 |
| 1983 | 28.3°C | 22.1°C | 15.9°C | 34.3°C | 10.0°C | 76 mm | 66% | 2.2 m/s | — |
| 1982 | 24.9°C | 18.7°C | 12.4°C | 31.5°C | 2.9°C | 95 mm | 67% | 2.5 m/s | — |
| 1981 | 26.5°C | 20.6°C | 14.8°C | 31.2°C | 8.6°C | 91 mm | 67% | 2.2 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 27.5°C with lows near 15.2°C (mean 21.4°C), based on 45 years of NASA POWER data.
August averages 66 mm of rainfall in Guelph, about average for rainfall. The wettest on record was 116 mm in 1992.
The hottest August reached 38.3°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 27°C to 28.3°C and overnight lows from 14.6°C to 16°C over the same span.
August is one of the warmer months of the year in Guelph and about average for rainfall, so plan for around 27.5°C daytime highs and 15.2°C at night.
Not quite — August is the 11th coolest month in Guelph, averaging 21.4°C.
For August in Guelph, pack light layers you can adjust through the day, with typical highs of 27.5°C and lows of 15.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 66% — moderately humid.
Average wind speed in August is 2.4 m/s. The windiest August on record averaged 3 m/s (1987).
The wettest August on record was 1992 with 116 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 Guelph 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.
