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May Weather in St. Catharines, Canada

Last updated: June 18, 2025

In St. Catharines, Canada, the average temperature in May hovers around 12°C (54°F), with a minimum dipping to 0°C (33°F) and a pleasant maximum reaching 24°C (75°F). Expect 101 mm (4.0 in) of precipitation spread over 13 days, contributing to an average humidity level of 82%. Perfect for those who enjoy a refreshing climate!

May Temperature in St. Catharines

In May, in St. Catharines, the average temperature is 12°C (54°F). Maximum temperatures can reach 24°C (75°F), and minimums can drop as low as 0°C (33°F). Be prepared for a range of temperatures, making it essential to pack layers for your travels.

May Weather in St. Catharines: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in St. Catharines, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In St. Catharines, May typically has an average temperature of 12°C (54°F), with highs reaching up to 24°C (75°F) and lows dropping to around 0°C (33°F).
JanFebMarAprMayJunJulAugSepOctNovDec282935435365737266554234
Data source: Temperature data for St. Catharines 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.

May Precipitation in St. Catharines

In St. Catharines in May, the precipitation amount is 101 mm (4.0 in) over the course of 13 days.

May Precipitation Trends in St. Catharines

The chart displays monthly precipitation patterns in St. Catharines, 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 St. Catharines, May typically receives around 101 mm (4.0 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec7786711191018210680691268686
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in St. Catharines

In St. Catharines in May humidity is 82%. With an average temperature of 12°C (54°F), this humidity feels like a heavy blanket wrapping around you, making every step feel sluggish and sweat-inducing, which can be quite uncomfortable for traveling.

May Average Humidity in St. Catharines

This chart illustrates the average monthly humidity levels in St. Catharines, 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 St. Catharines is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%91%88%88%82%80%77%72%76%83%88%87%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in St. Catharines

In St. Catharines in May, 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 St. Catharines.

Maximum UV Index Levels in St. Catharines for May

The chart shows the monthly maximum UV Index (UVI) for St. Catharines 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 St. Catharines typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2458910997532
Data source: St. Catharines 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 St. Catharines Compares to Other Months

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

This table compares monthly weather conditions in St. Catharines, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)77 mm (3.0 inches)91%low
February Weather-2°C (29°F)86 mm (3.4 inches)91%moderate
March Weather1°C (35°F)71 mm (2.8 inches)88%moderate
April Weather6°C (43°F)119 mm (4.7 inches)88%very high
May Weather12°C (54°F)101 mm (4.0 inches)82%very high
June Weather18°C (65°F)82 mm (3.2 inches)79%very high
July Weather23°C (73°F)106 mm (4.2 inches)77%very high
August Weather22°C (72°F)80 mm (3.1 inches)72%very high
September Weather19°C (66°F)69 mm (2.7 inches)76%high
October Weather13°C (56°F)126 mm (4.9 inches)83%moderate
November Weather5°C (42°F)86 mm (3.4 inches)88%moderate
December Weather1°C (35°F)86 mm (3.4 inches)87%low

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