April Weather in Ontario, United States

Last updated: June 24, 2025

In April, the average temperature in Ontario, United States is a cool 12°C (55°F), with temperatures ranging from a chilly -2°C (28°F) to a toasty 33°C (92°F). Expect 23 mm (0.9 in) of precipitation spread across 6 days, and be prepared for a high average humidity of 79%.

April Temperature in Ontario

In April in Ontario, the average temperature is 12°C (55°F), with maximums reaching up to 33°C (92°F) and minimums dropping as low as -2°C (28°F). This wide range of temperatures makes it essential for travelers to pack layers to stay comfortable throughout their visit.

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

The chart illustrates April 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, April typically has an average temperature of 12°C (55°F), with highs reaching up to 33°C (92°F) and lows dropping to around -2°C (28°F).

Data source: Temperature data for Ontario generated using information from the Copernicus Climate Change Service.

April Precipitation in Ontario

In Ontario in April, the precipitation amount is 23 mm (0.9 in) spread over 6 days.

April Precipitation Trends in Ontario

The chart displays monthly precipitation patterns in Ontario, with values for each month alongside April’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how April’s conditions compare to those of other months. In Ontario, April typically receives around 23 mm (0.9 inches) of precipitation spread over approximately 6 days.

Data source: Precipitation data for April generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

April Humidity in Ontario

In Ontario in April, humidity is 79%. With an average temperature of 12°C (55°F), this humidity feels like a damp chill that can make traveling uncomfortable; it can leave you feeling slightly clammy and require you to dress in layers to stay warm while navigating the thick, moisture-laden air.

April Average Humidity in Ontario

This chart illustrates the average monthly humidity levels in Ontario, with April’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In April, average humidity in Ontario is approximately 79%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for April generated using information from the Copernicus Climate Change Service.

April UV Index in Ontario

In Ontario in April, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Ontario.

Maximum UV Index Levels in Ontario for April

The chart shows the monthly maximum UV Index (UVI) for Ontario in April, 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 April, the maximum UV index in Ontario typically reaches 7, which falls under the high exposure category.

Data source: Ontario April 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 April 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 April’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 April’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (33°F)	42 mm (1.7 inches)	88%	moderate
February Weather	2°C (36°F)	46 mm (1.8 inches)	89%	moderate
March Weather	8°C (47°F)	32 mm (1.3 inches)	85%	high
April Weather	12°C (55°F)	23 mm (0.9 inches)	79%	high
May Weather	17°C (64°F)	28 mm (1.1 inches)	71%	very high
June Weather	23°C (73°F)	16 mm (0.6 inches)	71%	extreme
July Weather	29°C (84°F)	1 mm (0.0 inches)	66%	very high
August Weather	27°C (82°F)	5 mm (0.2 inches)	50%	very high
September Weather	21°C (70°F)	10 mm (0.4 inches)	48%	very high
October Weather	12°C (55°F)	16 mm (0.6 inches)	65%	moderate
November Weather	6°C (43°F)	27 mm (1.1 inches)	84%	moderate
December Weather	1°C (35°F)	29 mm (1.1 inches)	87%	low