August is one of the warmer months of the year in St. Catharines, with average highs near 25.5°C and lows around 17.4°C (mean 21.5°C). It is about average for rainfall, averaging 69 mm of rainfall and 71% relative humidity across the period.
August is one of the warmer months of the year in St. Catharines. Across 45 years of records, the warmest August in St. Catharines was 2016 — when the month averaged 24.7°C — while the coldest was 1992 at 17.2°C. Typical August days reach 25.5°C with nights near 17.4°C. The long-term trend is warming, about 0.7°C per decade.
August is about average for rainfall in St. Catharines, averaging 69 mm of rainfall. The wettest August on record was 2009 with 135 mm, while the driest was 1996 at 31 mm.
Relative humidity in St. Catharines during August averages 71%. The most humid August was 1992 at 78%, and the least humid was 2025 at 62%.
August receives about 5.2 kWh/m²/day of solar energy in St. Catharines. The sunniest Augusts were 2002 and 2016 at 5.8 kWh/m²/day, and the cloudiest was 1997 at 4.6.
Average wind speed in St. Catharines during August is 2.7 m/s. The windiest August was 1987 at 3.2 m/s, while the calmest were 1996 and 2003 at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.6°C | 20.2°C | 21.5°C | 22.4°C | 23.1°C | +2.5°C |
| Avg High | 24.7°C | 24.5°C | 25.4°C | 26.3°C | 27.0°C | +2.3°C |
| Avg Low | 16.5°C | 15.9°C | 17.6°C | 18.7°C | 19.1°C | +2.6°C |
| Avg Rain | 77 mm | 63 mm | 76 mm | 70 mm | 56 mm | -21 mm |
August temperatures in St. Catharines have risen by about 2°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 8°C (1982) to a record high of 32.6°C (2012).
Rainfall in August is about average for rainfall, averaging 69 mm, with a wettest year of 135 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.6°C per decade while lows rose 0.9°C per decade, narrowing the gap between day and night.
One of the best times to visit St. Catharines
August is one of the best times to visit St. Catharines. Expect days averaging 25.5°C and nights around 17.4°C (mean 21.5°C) — warmer than St. Catharines's yearly average — with moderate rainfall (69 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 | 26.7°C | 22.7°C | 18.7°C | 31.9°C | 13.0°C | 43 mm | 62% | 2.7 m/s | 5.3 |
| 2024 | 26.6°C | 22.7°C | 18.7°C | 31.2°C | 14.2°C | 59 mm | 69% | 2.8 m/s | 4.8 |
| 2023 | 25.2°C | 21.4°C | 17.6°C | 28.2°C | 13.9°C | 79 mm | 71% | 3.1 m/s | 5 |
| 2022 | 27.5°C | 23.5°C | 19.5°C | 30.8°C | 16.0°C | 56 mm | 67% | 2.6 m/s | 5.3 |
| 2021 | 28.4°C | 24.6°C | 20.9°C | 31.6°C | 15.7°C | 51 mm | 71% | 2.5 m/s | 5.3 |
| 2020 | 27.5°C | 23.4°C | 19.2°C | 30.2°C | 16.2°C | 47 mm | 68% | 3 m/s | 5.6 |
| 2019 | 26.0°C | 22.2°C | 18.5°C | 28.9°C | 14.9°C | 78 mm | 72% | 2.9 m/s | 5.7 |
| 2018 | 27.0°C | 23.5°C | 20.1°C | 30.6°C | 16.2°C | 92 mm | 76% | 3 m/s | 4.9 |
| 2017 | 25.0°C | 21.2°C | 17.4°C | 28.7°C | 13.9°C | 67 mm | 71% | 3 m/s | 5.1 |
| 2016 🔥 | 28.8°C | 24.7°C | 20.7°C | 31.9°C | 16.4°C | 69 mm | 69% | 2.8 m/s | 5.8 |
| 2015 | 25.3°C | 21.6°C | 17.9°C | 29.9°C | 14.4°C | 60 mm | 71% | 2.9 m/s | 5.2 |
| 2014 | 24.8°C | 21.0°C | 17.1°C | 28.9°C | 13.6°C | 52 mm | 74% | 2.7 m/s | 5.1 |
| 2013 | 25.3°C | 21.4°C | 17.6°C | 28.2°C | 13.0°C | 81 mm | 72% | 2.7 m/s | 5.4 |
| 2012 | 26.9°C | 22.8°C | 18.8°C | 32.6°C | 15.8°C | 58 mm | 67% | 2.7 m/s | 5.4 |
| 2011 | 26.5°C | 22.8°C | 19.1°C | 31.1°C | 15.3°C | 86 mm | 70% | 2.8 m/s | 5.1 |
| 2010 | 27.2°C | 23.3°C | 19.4°C | 30.8°C | 14.8°C | 60 mm | 70% | 2.9 m/s | 5.1 |
| 2009 🌧️ | 24.8°C | 21.5°C | 18.3°C | 30.0°C | 13.6°C | 135 mm | 76% | 2.8 m/s | 5.2 |
| 2008 | 24.5°C | 20.8°C | 17.1°C | 28.9°C | 13.3°C | 87 mm | 72% | 2.7 m/s | 5.5 |
| 2007 | 26.9°C | 22.9°C | 18.8°C | 31.7°C | 13.6°C | 40 mm | 68% | 2.7 m/s | 5.2 |
| 2006 | 25.7°C | 22.1°C | 18.5°C | 31.6°C | 13.9°C | 76 mm | 70% | 3 m/s | 5.4 |
| 2005 | 27.7°C | 23.6°C | 19.5°C | 31.5°C | 15.7°C | 100 mm | 67% | 2.8 m/s | 5.1 |
| 2004 | 23.6°C | 20.3°C | 17.0°C | 27.4°C | 13.7°C | 64 mm | 75% | 2.8 m/s | 4.7 |
| 2003 | 24.9°C | 20.8°C | 16.7°C | 28.7°C | 12.8°C | 60 mm | 76% | 2.1 m/s | 5.3 |
| 2002 | 25.4°C | 20.9°C | 16.4°C | 29.1°C | 12.9°C | 40 mm | 69% | 2.6 m/s | 5.8 |
| 2001 | 25.9°C | 21.3°C | 16.7°C | 30.9°C | 13.1°C | 67 mm | 69% | 2.5 m/s | 5.4 |
| 2000 | 24.4°C | 20.9°C | 17.4°C | 29.7°C | 12.9°C | 96 mm | 74% | 2.9 m/s | 5.1 |
| 1999 | 23.6°C | 19.4°C | 15.3°C | 28.2°C | 11.6°C | 66 mm | 70% | 2.6 m/s | 4.9 |
| 1998 | 26.8°C | 23.0°C | 19.1°C | 31.2°C | 14.3°C | 51 mm | 67% | 2.5 m/s | 5.3 |
| 1997 | 24.3°C | 20.5°C | 16.7°C | 28.7°C | 13.8°C | 63 mm | 70% | 3 m/s | 4.6 |
| 1996 | 25.2°C | 20.3°C | 15.5°C | 28.9°C | 12.3°C | 31 mm | 71% | 2.1 m/s | 5.6 |
| 1995 | 26.4°C | 21.9°C | 17.4°C | 29.8°C | 12.3°C | 45 mm | 69% | 2.5 m/s | 5.1 |
| 1994 | 23.0°C | 18.7°C | 14.4°C | 26.1°C | 10.6°C | 73 mm | 74% | 2.7 m/s | 5.2 |
| 1993 | 25.5°C | 21.0°C | 16.4°C | 30.0°C | 11.9°C | 47 mm | 68% | 2.2 m/s | 5.6 |
| 1992 ❄️ | 21.4°C | 17.2°C | 13.0°C | 27.3°C | 9.6°C | 106 mm | 78% | 2.9 m/s | 5.1 |
| 1991 | 24.5°C | 20.0°C | 15.5°C | 29.7°C | 11.8°C | 63 mm | 71% | 2.8 m/s | 5.3 |
| 1990 | 24.2°C | 19.9°C | 15.7°C | 27.3°C | 12.7°C | 84 mm | 75% | 2.3 m/s | 5 |
| 1989 | 23.9°C | 19.4°C | 14.9°C | 26.8°C | 9.9°C | 46 mm | 72% | 2.8 m/s | 5 |
| 1988 | 24.9°C | 20.8°C | 16.6°C | 30.9°C | 11.0°C | 70 mm | 71% | 2.9 m/s | 5.2 |
| 1987 | 24.4°C | 20.1°C | 15.9°C | 30.2°C | 10.1°C | 72 mm | 69% | 3.2 m/s | 4.9 |
| 1986 | 23.8°C | 19.9°C | 16.1°C | 28.7°C | 9.0°C | 91 mm | 72% | 3.1 m/s | 5.1 |
| 1985 | 24.9°C | 20.8°C | 16.7°C | 29.4°C | 13.0°C | 82 mm | 68% | 2.8 m/s | 5 |
| 1984 | 26.1°C | 22.1°C | 18.1°C | 29.9°C | 13.3°C | 65 mm | 72% | 2.6 m/s | 5.4 |
| 1983 | 26.0°C | 22.0°C | 18.0°C | 28.9°C | 14.7°C | 101 mm | 72% | 2.5 m/s | — |
| 1982 | 23.5°C | 19.3°C | 15.1°C | 28.5°C | 8.0°C | 90 mm | 69% | 3 m/s | — |
| 1981 | 24.5°C | 20.7°C | 16.8°C | 27.5°C | 12.1°C | 78 mm | 73% | 2.7 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 25.5°C with lows near 17.4°C (mean 21.5°C), based on 45 years of NASA POWER data.
August averages 69 mm of rainfall in St. Catharines, about average for rainfall. The wettest on record was 135 mm in 2009.
The hottest August reached 32.6°C in 2012. The coldest dipped to 8°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 2°C. Daytime highs moved from 25°C to 26.9°C and overnight lows from 16.9°C to 19.1°C over the same span.
August is one of the warmer months of the year in St. Catharines and about average for rainfall, so plan for around 25.5°C daytime highs and 17.4°C at night.
Not quite — August is the 11th coolest month in St. Catharines, averaging 21.5°C.
For August in St. Catharines, pack light layers you can adjust through the day, with typical highs of 25.5°C and lows of 17.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 71% — moderately humid.
Average wind speed in August is 2.7 m/s. The windiest August on record averaged 3.2 m/s (1987).
The wettest August on record was 2009 with 135 mm. On average, August sees 69 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 St. Catharines 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.
