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May Weather in Saint John, United States

Last updated: June 24, 2025

In Saint John, United States, the average temperature in May hovers around 18°C (65°F). However, temperatures can range from a chilly 2°C (35°F) to a sweltering 35°C (95°F). Expect about 168 mm (6.6 in) of precipitation spread over 12 days, contributing to an average humidity of 82%. ☔️🌡️

May Temperature in Saint John

In May in Saint John, the average temperature is 18°C (65°F). Maximum temperatures can reach 35°C (95°F), while minimums can drop as low as 2°C (35°F). Be prepared for a wide range of temperatures during your travels, so pack accordingly!

May Weather in Saint John: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Saint John, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint John, May typically has an average temperature of 18°C (65°F), with highs reaching up to 35°C (95°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec323346546577817873564537
Data source: Temperature data for Saint John 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 Saint John

In Saint John in May, the precipitation amount is 168 mm (6.6 in) over the course of 12 days.

May Precipitation Trends in Saint John

The chart displays monthly precipitation patterns in Saint John, 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 Saint John, May typically receives around 168 mm (6.6 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec2621685016862587462812432
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Saint John

In Saint John in May, humidity is 82%. With an average temperature of 18°C (65°F), this humidity feels like a warm, sticky embrace that can quickly leave travelers feeling fatigued and in need of frequent breaks to stay refreshed and hydrated.

May Average Humidity in Saint John

This chart illustrates the average monthly humidity levels in Saint John, 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 Saint John is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec75%76%67%70%82%82%81%76%67%72%80%83%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Saint John

In Saint John 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 Saint John.

Maximum UV Index Levels in Saint John for May

The chart shows the monthly maximum UV Index (UVI) for Saint John 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 Saint John typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec4579101111109753
Data source: Saint John 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 Saint John Compares to Other Months

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

This table compares monthly weather conditions in Saint John, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)25 mm (1.0 inches)75%moderate
February Weather1°C (34°F)21 mm (0.8 inches)76%moderate
March Weather8°C (47°F)68 mm (2.7 inches)67%high
April Weather12°C (54°F)50 mm (2.0 inches)70%very high
May Weather18°C (65°F)168 mm (6.6 inches)82%very high
June Weather25°C (77°F)62 mm (2.4 inches)82%extreme
July Weather27°C (81°F)58 mm (2.3 inches)81%extreme
August Weather25°C (78°F)74 mm (2.9 inches)76%very high
September Weather23°C (73°F)62 mm (2.4 inches)67%very high
October Weather14°C (57°F)81 mm (3.2 inches)72%high
November Weather7°C (45°F)24 mm (0.9 inches)80%moderate
December Weather3°C (37°F)32 mm (1.3 inches)83%moderate

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