May Weather in Portola, United States

Last updated: June 24, 2025

In May, the average temperature in Portola, United States is a cool 10°C (51°F). Expect chilly lows of -7°C (20°F) and pleasant highs reaching up to 28°C (83°F). During this month, 60 mm (2.3 in) of precipitation is likely over 9 days, contributing to an average humidity of 74%. Be prepared for a mix of weather as you explore the beauty of Portola!

May Temperature in Portola

In May in Portola, the average temperature is 10°C (51°F). Maximum temperatures can reach 28°C (83°F), while minimums can drop to as low as -7°C (20°F). Be prepared for a wide range of temperatures, making it essential to pack accordingly for your travels.

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

The chart illustrates May temperature patterns in Portola, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portola, May typically has an average temperature of 10°C (51°F), with highs reaching up to 28°C (83°F) and lows dropping to around -7°C (20°F).

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

May Precipitation in Portola

In Portola in May, the total precipitation amount is 60 mm (2.3 in), occurring over the course of 9 days.

May Precipitation Trends in Portola

The chart displays monthly precipitation patterns in Portola, 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 Portola, May typically receives around 60 mm (2.3 inches) of precipitation spread over approximately 9 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 Portola

In Portola in May humidity is 74%. With an average temperature of 10°C (51°F), this humidity feels like a damp chill enveloping you, making travel a bit uncomfortable as the cold air clings to your skin, and you may find yourself wishing you had packed an extra layer to stay warm and dry.

May Average Humidity in Portola

This chart illustrates the average monthly humidity levels in Portola, 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 Portola is approximately 74%, 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 Portola

In Portola 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 Portola.

Maximum UV Index Levels in Portola for May

The chart shows the monthly maximum UV Index (UVI) for Portola 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 Portola typically reaches 12, which falls under the extreme exposure category.

Data source: Portola 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 Portola Compares to Other Months

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

This table compares monthly weather conditions in Portola, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-1°C (31°F)	170 mm (6.7 inches)	84%	moderate
February Weather	-1°C (30°F)	177 mm (7.0 inches)	84%	high
March Weather	1°C (34°F)	146 mm (5.7 inches)	83%	very high
April Weather	5°C (41°F)	72 mm (2.8 inches)	81%	very high
May Weather	10°C (51°F)	60 mm (2.3 inches)	74%	extreme
June Weather	16°C (62°F)	10 mm (0.4 inches)	64%	extreme
July Weather	21°C (70°F)	10 mm (0.4 inches)	44%	extreme
August Weather	20°C (68°F)	13 mm (0.5 inches)	36%	extreme
September Weather	15°C (60°F)	19 mm (0.7 inches)	44%	very high
October Weather	8°C (47°F)	43 mm (1.7 inches)	65%	high
November Weather	3°C (38°F)	79 mm (3.1 inches)	84%	moderate
December Weather	-2°C (29°F)	132 mm (5.2 inches)	83%	moderate