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April Weather in Portola Valley, United States

Last updated: June 24, 2025

In April, the average temperature in Portola Valley, United States is a pleasant 13°C (57°F), with minimums dipping to 6°C (42°F) and highs reaching up to 30°C (87°F). Prepare for a bit of rain, as precipitation averages around 33 mm (1.3 in) over 5 days. Also, expect a comfortable average humidity level of 78%.

April Temperature in Portola Valley

In April in Portola Valley, the average temperature is 13°C (57°F). The maximum can reach 30°C (87°F), while the minimum can be as low as 6°C (42°F). Be prepared for a range of temperatures, making it a great time for layering your clothing when traveling.

April Weather in Portola Valley: Daily Temperature Highs, Lows, and Averages

The chart illustrates April temperature patterns in Portola Valley, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portola Valley, April typically has an average temperature of 13°C (57°F), with highs reaching up to 30°C (87°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec525354565863636565625652
Data source: Temperature data for Portola Valley 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.

April Precipitation in Portola Valley

In Portola Valley in April, the precipitation amount is 33 mm (1.3 in) over the course of 5 days.

April Precipitation Trends in Portola Valley

The chart displays monthly precipitation patterns in Portola Valley, with values for each month alongside April’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how April’s conditions compare to those of other months. In Portola Valley, April typically receives around 33 mm (1.3 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec1051008633242012244788
Data source: Precipitation data for April generated using information from the Copernicus Climate Change Service.
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April Humidity in Portola Valley

In Portola Valley in April, humidity is 78%. With an average temperature of 13°C (57°F), this humidity feels like a damp chill that clings to your skin, making outdoor activities a bit uncomfortable and requiring a light jacket to stay warm while exploring.

April Average Humidity in Portola Valley

This chart illustrates the average monthly humidity levels in Portola Valley, with April’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In April, average humidity in Portola Valley is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%84%82%78%71%64%59%54%55%62%78%80%
Data source: Humidity data for April generated using information from the Copernicus Climate Change Service.

April UV Index in Portola Valley

In Portola Valley in April, 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 Portola Valley.

Maximum UV Index Levels in Portola Valley for April

The chart shows the monthly maximum UV Index (UVI) for Portola Valley in April, 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 April, the maximum UV index in Portola Valley typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3589101111109743
Data source: Portola Valley April 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 April Weather in Portola Valley Compares to Other Months

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

This table compares monthly weather conditions in Portola Valley, showing how April’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather11°C (52°F)105 mm (4.1 inches)82%moderate
February Weather11°C (53°F)100 mm (3.9 inches)84%moderate
March Weather12°C (54°F)86 mm (3.4 inches)82%very high
April Weather13°C (57°F)33 mm (1.3 inches)78%very high
May Weather15°C (59°F)24 mm (0.9 inches)71%very high
June Weather17°C (63°F)2 mm (0.1 inches)64%extreme
July Weather17°C (63°F)0 mm (0.0 inches)58%extreme
August Weather18°C (65°F)0 mm (0.0 inches)54%very high
September Weather18°C (66°F)2 mm (0.1 inches)55%very high
October Weather17°C (63°F)24 mm (0.9 inches)62%high
November Weather13°C (56°F)47 mm (1.9 inches)78%moderate
December Weather11°C (52°F)88 mm (3.5 inches)80%moderate

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