May Weather in Johnston, United States

Last updated: June 24, 2025

In May, the average temperature in Johnston, United States hovers around 23°C (74°F), providing a pleasant climate. However, be prepared for a range of weather, with minimums dipping to 6°C (43°F) and highs reaching up to 38°C (100°F). Expect approximately 110 mm (4.3 in) of precipitation spread over 10 days, and note that the average humidity is a comfortable 75%. Pack accordingly to enjoy your stay!

May Temperature in Johnston

In May in Johnston, the average temperature is 23°C (74°F). Maximum temperatures can reach up to 38°C (100°F), while minimums can drop as low as 6°C (43°F). This range makes it essential to pack accordingly for your travels, ensuring you are prepared for both warm days and cooler nights.

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 23°C (74°F), with highs reaching up to 38°C (100°F) and lows dropping to around 6°C (43°F).

Data source: Temperature data for Johnston generated using information from the Copernicus Climate Change Service.

May Precipitation in Johnston

In Johnston in May, the precipitation amount is 110 mm (4.3 in) over a period of 10 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 110 mm (4.3 inches) of precipitation spread over approximately 10 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

May Humidity in Johnston

In Johnston in May, humidity is 75%. With an average temperature of 23°C (74°F), this humidity feels like a warm, heavy blanket wrapping around you, making it feel more sweltering than it actually is, which can be quite uncomfortable for traveling.

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.

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 reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, 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 11, which falls under the extreme exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	84 mm (3.3 inches)	86%	moderate
February Weather	12°C (54°F)	114 mm (4.5 inches)	81%	high
March Weather	14°C (58°F)	85 mm (3.4 inches)	81%	very high
April Weather	18°C (65°F)	115 mm (4.5 inches)	79%	very high
May Weather	23°C (74°F)	110 mm (4.3 inches)	75%	extreme
June Weather	26°C (79°F)	101 mm (4.0 inches)	75%	extreme
July Weather	28°C (82°F)	137 mm (5.4 inches)	80%	extreme
August Weather	27°C (80°F)	142 mm (5.6 inches)	81%	extreme
September Weather	25°C (77°F)	84 mm (3.3 inches)	83%	very high
October Weather	20°C (69°F)	80 mm (3.1 inches)	78%	very high
November Weather	13°C (55°F)	69 mm (2.7 inches)	85%	high
December Weather	10°C (51°F)	119 mm (4.7 inches)	87%	moderate