May Weather in Rialto, United States

Last updated: June 24, 2025

In May, the average temperature in Rialto, United States is a pleasant 18°C (64°F). However, be prepared for a range, as temperatures can dip to a minimum of 4°C (40°F) and rise to a maximum of 33°C (92°F). With an average humidity of 46%, you can expect comfortable conditions, although there may be 18 mm (0.7 in) of precipitation spread over 3 days.

May Temperature in Rialto

In May in Rialto, the average temperature is 18°C (64°F). The maximum can reach 33°C (92°F) and the minimum can be as low as 4°C (40°F). This makes it an ideal time for travelers seeking a pleasant climate while enjoying outdoor activities.

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

The chart illustrates May temperature patterns in Rialto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Rialto, May typically has an average temperature of 18°C (64°F), with highs reaching up to 33°C (92°F) and lows dropping to around 4°C (40°F).

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

May Precipitation in Rialto

In Rialto in May, the precipitation amount is 18 mm (0.7 in) over a span of 3 days.

May Precipitation Trends in Rialto

The chart displays monthly precipitation patterns in Rialto, 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 Rialto, May typically receives around 18 mm (0.7 inches) of precipitation spread over approximately 3 days.

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

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Millimeters (mm) Inches (in)

May Humidity in Rialto

In Rialto in May humidity is 46%. With an average temperature of 18°C (64°F), this humidity feels like a pleasant and comfortable experience for traveling, allowing for enjoyable outdoor activities without feeling overly sticky or oppressive.

May Average Humidity in Rialto

This chart illustrates the average monthly humidity levels in Rialto, 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 Rialto is approximately 46%, 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 Rialto

In Rialto 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 Rialto.

Maximum UV Index Levels in Rialto for May

The chart shows the monthly maximum UV Index (UVI) for Rialto 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 Rialto typically reaches 11, which falls under the extreme exposure category.

Data source: Rialto 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 Rialto Compares to Other Months

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

This table compares monthly weather conditions in Rialto, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	11°C (51°F)	70 mm (2.8 inches)	72%	moderate
February Weather	11°C (52°F)	70 mm (2.7 inches)	77%	high
March Weather	12°C (54°F)	75 mm (2.9 inches)	67%	very high
April Weather	16°C (61°F)	31 mm (1.2 inches)	56%	very high
May Weather	18°C (64°F)	18 mm (0.7 inches)	46%	extreme
June Weather	22°C (72°F)	3 mm (0.1 inches)	48%	extreme
July Weather	26°C (78°F)	11 mm (0.4 inches)	46%	extreme
August Weather	26°C (79°F)	10 mm (0.4 inches)	42%	extreme
September Weather	23°C (74°F)	10 mm (0.4 inches)	52%	very high
October Weather	19°C (66°F)	11 mm (0.4 inches)	58%	very high
November Weather	15°C (59°F)	28 mm (1.1 inches)	66%	moderate
December Weather	11°C (51°F)	70 mm (2.7 inches)	74%	moderate