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May Weather in Cornwall, Canada

Last updated: June 18, 2025

In May, the average temperature in Cornwall, Canada hovers around 14°C (57°F), making it a mild time of year. Be prepared for some temperature swings, as the minimum can dip to -1°C (30°F), while the mercury can soar to a maximum of 35°C (96°F). Rainfall is also noteworthy, with approximately 109 mm (4.3 in) expected over about 13 days, contributing to an average humidity level of 80%.

May Temperature in Cornwall

In May in Cornwall, the average temperature is 14°C (57°F). Maximum temperatures can reach 35°C (96°F), while minimums can drop as low as -1°C (30°F). Pack accordingly to enjoy a variety of outdoor activities and experiences during your trip.

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

The chart illustrates May temperature patterns in Cornwall, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Cornwall, May typically has an average temperature of 14°C (57°F), with highs reaching up to 35°C (96°F) and lows dropping to around -1°C (30°F).
JanFebMarAprMayJunJulAugSepOctNovDec192230435766716962503626
Data source: Temperature data for Cornwall 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 Cornwall

In Cornwall in May, the precipitation amount is 109 mm (4.3 in), which occurs during 13 days.

May Precipitation Trends in Cornwall

The chart displays monthly precipitation patterns in Cornwall, 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 Cornwall, May typically receives around 109 mm (4.3 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec8583871171091001161007013910884
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Cornwall

In Cornwall in May, humidity is 80%. With an average temperature of 14°C (57°F), this humidity feels like a warm, damp blanket wrapping around you, making travel uncomfortable and sticky, as sweat clings to your skin and the air feels heavy with moisture.

May Average Humidity in Cornwall

This chart illustrates the average monthly humidity levels in Cornwall, 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 Cornwall is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%92%86%85%80%74%76%75%78%86%89%89%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Cornwall

In Cornwall 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 Cornwall.

Maximum UV Index Levels in Cornwall for May

The chart shows the monthly maximum UV Index (UVI) for Cornwall 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 Cornwall typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec245899987532
Data source: Cornwall 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 Cornwall Compares to Other Months

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

This table compares monthly weather conditions in Cornwall, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-7°C (20°F)85 mm (3.3 inches)93%low
February Weather-6°C (22°F)83 mm (3.3 inches)92%moderate
March Weather-1°C (30°F)87 mm (3.4 inches)86%moderate
April Weather6°C (44°F)117 mm (4.6 inches)85%very high
May Weather14°C (57°F)109 mm (4.3 inches)80%very high
June Weather19°C (66°F)100 mm (3.9 inches)74%very high
July Weather22°C (72°F)116 mm (4.6 inches)76%very high
August Weather21°C (70°F)100 mm (3.9 inches)75%very high
September Weather16°C (62°F)70 mm (2.8 inches)78%high
October Weather10°C (51°F)139 mm (5.5 inches)86%moderate
November Weather2°C (36°F)108 mm (4.2 inches)88%moderate
December Weather-3°C (26°F)84 mm (3.3 inches)89%low

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