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May Weather in Johnston, United States

Last updated: June 24, 2025

In Johnston, United States, the average temperature in May is a comfortable 15°C (59°F). Expect a range of temperatures, with a minimum of 2°C (35°F) and a maximum reaching up to 33°C (92°F). During this time, anticipate 103 mm (4.1 in) of precipitation spread over 12 days, contributing to an average humidity of 75%.

May Temperature in Johnston

In May in Johnston, the average temperature is 15°C (59°F). Maximum temperatures can reach up to 33°C (92°F), while minimums can dip as low as 2°C (35°F). This varied climate makes Johnston a great destination for travelers seeking both warm and cool experiences.

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

The chart illustrates May temperature patterns in Johnston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Johnston, May typically has an average temperature of 15°C (59°F), with highs reaching up to 33°C (92°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec323439485968747366574435
Data source: Temperature data for Johnston 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 Johnston

In Johnston in May, the total precipitation amount is 103 mm (4.1 in), occurring over the course of 12 days.

May Precipitation Trends in Johnston

The chart displays monthly precipitation patterns in Johnston, 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 Johnston, May typically receives around 103 mm (4.1 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec739099128103981301029313399121
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Johnston

In Johnston in May, humidity is 75%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket enveloping you, making it feel more oppressive than refreshing, which can be a challenge for travelers seeking comfort while exploring the area.

May Average Humidity in Johnston

This chart illustrates the average monthly humidity levels in Johnston, 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 Johnston is approximately 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%82%79%75%78%76%76%76%75%80%80%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Johnston

In Johnston 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 Johnston.

Maximum UV Index Levels in Johnston for May

The chart shows the monthly maximum UV Index (UVI) for Johnston 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 Johnston typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3568910998642
Data source: Johnston 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 Johnston Compares to Other Months

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

This table compares monthly weather conditions in Johnston, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (32°F)73 mm (2.9 inches)84%moderate
February Weather1°C (34°F)90 mm (3.5 inches)84%moderate
March Weather4°C (39°F)99 mm (3.9 inches)82%high
April Weather9°C (49°F)127 mm (5.0 inches)79%very high
May Weather15°C (59°F)103 mm (4.1 inches)75%very high
June Weather20°C (68°F)98 mm (3.8 inches)78%very high
July Weather23°C (74°F)130 mm (5.1 inches)76%very high
August Weather23°C (74°F)101 mm (4.0 inches)76%very high
September Weather19°C (67°F)93 mm (3.7 inches)75%very high
October Weather14°C (57°F)133 mm (5.3 inches)75%high
November Weather7°C (44°F)99 mm (3.9 inches)80%moderate
December Weather2°C (36°F)121 mm (4.8 inches)80%low

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