May Weather in Ottawa, United States

Last updated: June 24, 2025

In May, the average temperature in Ottawa, United States hovers around 19°C (66°F), but be prepared for a range that can dip as low as 3°C (38°F) and soar up to 34°C (93°F). With 196 mm (7.7 in) of precipitation over about 14 days, it’s wise to expect some rain during your visit. Additionally, the average humidity level sits at a comfortable 82%, making it a noteworthy month for weather!

May Temperature in Ottawa

In May in Ottawa, the average temperature is 19°C (66°F). Maximums can reach 34°C (93°F), while minimums can dip to as low as 3°C (38°F). This variability makes Ottawa a great destination for travelers who enjoy diverse weather experiences.

May Weather in Ottawa: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Ottawa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ottawa, May typically has an average temperature of 19°C (66°F), with highs reaching up to 34°C (93°F) and lows dropping to around 3°C (38°F).

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

May Precipitation in Ottawa

In Ottawa in May, the total precipitation amount is 196 mm (7.7 in) occurring over the course of 14 days.

May Precipitation Trends in Ottawa

The chart displays monthly precipitation patterns in Ottawa, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Ottawa, May typically receives around 196 mm (7.7 inches) of precipitation spread over approximately 14 days.

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

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Millimeters (mm) Inches (in)

May Humidity in Ottawa

In Ottawa in May humidity is 82%. With an average temperature of 19°C (66°F), this humidity feels like a warm blanket wrapping around you, making it slightly uncomfortable for traveling as you might find yourself constantly seeking shade or a cool breeze.

May Average Humidity in Ottawa

This chart illustrates the average monthly humidity levels in Ottawa, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Ottawa is approximately 82%, offering insight into how humid the weather typically is during this month.

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

May UV Index in Ottawa

In Ottawa in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Ottawa.

Maximum UV Index Levels in Ottawa for May

The chart shows the monthly maximum UV Index (UVI) for Ottawa in May, 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 May, the maximum UV index in Ottawa typically reaches 10, which falls under the very high exposure category.

Data source: Ottawa May 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 May Weather in Ottawa Compares to Other Months

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

This table compares monthly weather conditions in Ottawa, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (33°F)	56 mm (2.2 inches)	76%	moderate
February Weather	1°C (34°F)	36 mm (1.4 inches)	77%	high
March Weather	9°C (48°F)	98 mm (3.9 inches)	70%	high
April Weather	13°C (55°F)	96 mm (3.8 inches)	73%	very high
May Weather	19°C (66°F)	196 mm (7.7 inches)	82%	very high
June Weather	25°C (77°F)	109 mm (4.3 inches)	82%	extreme
July Weather	27°C (80°F)	112 mm (4.4 inches)	81%	extreme
August Weather	25°C (77°F)	120 mm (4.7 inches)	78%	very high
September Weather	22°C (73°F)	81 mm (3.2 inches)	71%	very high
October Weather	14°C (58°F)	115 mm (4.5 inches)	71%	high
November Weather	7°C (45°F)	41 mm (1.6 inches)	81%	moderate
December Weather	4°C (39°F)	33 mm (1.3 inches)	84%	moderate