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August Weather in Ontario, United States

Last updated: June 24, 2025

In Ontario, United States, the average temperature in August is a comfortable 22°C (72°F), with nighttime lows dropping to 9°C (48°F) and daytime highs reaching up to 32°C (90°F). Expect about 89 mm (3.5 in) of precipitation spread over 12 days, adding to the region's average humidity of 78%. Embrace the pleasant weather while exploring all that this destination has to offer!

August Temperature in Ontario

In August in Ontario, the average temperature is 22°C (72°F), with maximums reaching 32°C (90°F) and minimums dropping as low as 9°C (48°F). This diverse range makes it a perfect time for travelers to enjoy both warm and cooler activities.

August Weather in Ontario: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in Ontario, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ontario, August typically has an average temperature of 22°C (72°F), with highs reaching up to 32°C (90°F) and lows dropping to around 9°C (48°F).
JanFebMarAprMayJunJulAugSepOctNovDec293240506270747267564135
Data source: Temperature data for Ontario generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

August Precipitation in Ontario

In Ontario in August, the precipitation amount is 89 mm (3.5 in) during 12 days of rainfall.

August Precipitation Trends in Ontario

The chart displays monthly precipitation patterns in Ontario, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Ontario, August typically receives around 89 mm (3.5 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec81981031301261411238980989292
Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.
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August Humidity in Ontario

In Ontario in August, humidity is 78%. With an average temperature of 22°C (72°F), this humidity feels like a warm blanket wrapped around you, making outdoor exploration a bit stifling but ultimately rewarding as you bask in the vibrant atmosphere.

August Average Humidity in Ontario

This chart illustrates the average monthly humidity levels in Ontario, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, average humidity in Ontario is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%87%88%81%82%81%78%78%82%89%86%
Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in Ontario

In Ontario in August, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Ontario.

Maximum UV Index Levels in Ontario for August

The chart shows the monthly maximum UV Index (UVI) for Ontario in August, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In August, the maximum UV index in Ontario typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
Data source: Ontario August UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How August Weather in Ontario Compares to Other Months

Weather in Ontario varies notably across the year, with each month offering distinct climate conditions. This page compares August’s weather to other months in Ontario, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Ontario, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)81 mm (3.2 inches)88%moderate
February Weather0°C (32°F)98 mm (3.8 inches)87%moderate
March Weather5°C (40°F)103 mm (4.1 inches)87%high
April Weather10°C (50°F)130 mm (5.1 inches)87%very high
May Weather17°C (62°F)126 mm (5.0 inches)81%very high
June Weather21°C (71°F)141 mm (5.5 inches)82%very high
July Weather24°C (75°F)123 mm (4.8 inches)81%very high
August Weather22°C (72°F)89 mm (3.5 inches)78%very high
September Weather20°C (67°F)80 mm (3.2 inches)78%very high
October Weather14°C (57°F)98 mm (3.9 inches)82%high
November Weather5°C (41°F)92 mm (3.6 inches)89%moderate
December Weather1°C (35°F)92 mm (3.6 inches)86%low

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