March Weather in Ontario, United States

Last updated: June 24, 2025

In March, the average temperature in Ontario, United States hovers around 5°C (40°F). Expect chilly lows of -14°C (7°F) and the occasional warm day reaching up to 23°C (74°F). Prepare for 103 mm (4.1 inches) of precipitation spread over 13 days, contributing to an average humidity level of 87%.

March Temperature in Ontario

In March in Ontario, the average temperature is 5°C (40°F). Maximum temperatures can reach 23°C (74°F), while minimums can drop as low as -14°C (7°F). Visitors should be prepared for a wide range of temperatures when traveling to Ontario during this month.

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

The chart illustrates March 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, March typically has an average temperature of 5°C (40°F), with highs reaching up to 23°C (74°F) and lows dropping to around -14°C (7°F).

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

March Precipitation in Ontario

In Ontario in March, the precipitation amount is 103 mm (4.1 in) spread over a duration of 13 days.

March Precipitation Trends in Ontario

The chart displays monthly precipitation patterns in Ontario, with values for each month alongside March’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how March’s conditions compare to those of other months. In Ontario, March typically receives around 103 mm (4.1 inches) of precipitation spread over approximately 13 days.

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

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Millimeters (mm) Inches (in)

March Humidity in Ontario

In Ontario in March, humidity is 87%. With an average temperature of 5°C (40°F), this humidity feels like a damp chill that wraps around you, making outdoor excursions less enjoyable and requiring extra layers to stay comfortable while exploring.

March Average Humidity in Ontario

This chart illustrates the average monthly humidity levels in Ontario, with March’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In March, average humidity in Ontario is approximately 87%, offering insight into how humid the weather typically is during this month.

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

March UV Index in Ontario

In Ontario in March, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Ontario, you can refer to this Hourly UV Index in Ontario.

Maximum UV Index Levels in Ontario for March

The chart shows the monthly maximum UV Index (UVI) for Ontario in March, 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 March, the maximum UV index in Ontario typically reaches 6, which falls under the high exposure category.

Data source: Ontario March 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 March 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 March’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 March’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-2°C (29°F)	81 mm (3.2 inches)	88%	moderate
February Weather	0°C (32°F)	98 mm (3.8 inches)	87%	moderate
March Weather	5°C (40°F)	103 mm (4.1 inches)	87%	high
April Weather	10°C (50°F)	130 mm (5.1 inches)	87%	very high
May Weather	17°C (62°F)	126 mm (5.0 inches)	81%	very high
June Weather	21°C (71°F)	141 mm (5.5 inches)	82%	very high
July Weather	24°C (75°F)	123 mm (4.8 inches)	81%	very high
August Weather	22°C (72°F)	89 mm (3.5 inches)	78%	very high
September Weather	20°C (67°F)	80 mm (3.2 inches)	78%	very high
October Weather	14°C (57°F)	98 mm (3.9 inches)	82%	high
November Weather	5°C (41°F)	92 mm (3.6 inches)	89%	moderate
December Weather	1°C (35°F)	92 mm (3.6 inches)	86%	low