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May Weather in Seiyo, Japan

Last updated: August 23, 2025

In May, the average temperature in Seiyo, Japan is a mild 18°C (65°F), with minimums dipping to 3°C (39°F) and highs reaching up to 30°C (86°F). Be prepared for some rain, as the area receives an average precipitation of 174 mm (6.8 in) over approximately 12 days. With an average humidity level of 82%, it’s a good idea to pack accordingly for a comfortable stay!

May Temperature in Seiyo

In May in Seiyo, the average temperature is 18°C (65°F). Maximums can reach 30°C (86°F), and minimums can drop as low as 3°C (39°F). This makes Seiyo an ideal destination for travelers seeking mild weather and the opportunity to experience a range of temperatures.

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

The chart illustrates May temperature patterns in Seiyo, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Seiyo, May typically has an average temperature of 18°C (65°F), with highs reaching up to 30°C (86°F) and lows dropping to around 3°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec394149576571778073645243
Data source: Temperature data for Seiyo 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 Seiyo

In Seiyo in May, the total precipitation amount is 174 mm (6.8 in), recorded over the course of 12 days.

May Precipitation Trends in Seiyo

The chart displays monthly precipitation patterns in Seiyo, 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 Seiyo, May typically receives around 174 mm (6.8 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec60971401401742364092192292136269
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Seiyo

In Seiyo 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 Seiyo

This chart illustrates the average monthly humidity levels in Seiyo, 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 Seiyo is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%70%70%76%83%86%91%88%85%82%79%77%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Seiyo

In Seiyo in May, the maximum UV index is 12, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, underscoring the importance of sun protection. For detailed information, you can check the Hourly UV Index in Seiyo.

Maximum UV Index Levels in Seiyo for May

The chart shows the monthly maximum UV Index (UVI) for Seiyo 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 Seiyo typically reaches 12, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec469101211121211864
Data source: Seiyo 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 Seiyo Compares to Other Months

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

This table compares monthly weather conditions in Seiyo, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather4°C (40°F)60 mm (2.4 inches)74%moderate
February Weather5°C (41°F)97 mm (3.8 inches)70%high
March Weather9°C (49°F)140 mm (5.5 inches)70%very high
April Weather14°C (57°F)140 mm (5.5 inches)76%very high
May Weather18°C (65°F)174 mm (6.8 inches)82%extreme
June Weather22°C (71°F)236 mm (9.3 inches)86%extreme
July Weather25°C (78°F)409 mm (16.1 inches)91%extreme
August Weather27°C (80°F)219 mm (8.6 inches)88%extreme
September Weather23°C (74°F)229 mm (9.0 inches)85%extreme
October Weather18°C (64°F)213 mm (8.4 inches)82%very high
November Weather11°C (52°F)62 mm (2.4 inches)79%high
December Weather6°C (43°F)69 mm (2.7 inches)77%moderate

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