Contents
- Weather in May
- Frequently asked questions
- Average temperature in May
- Average pressure in May
- Average wind speed in May
- Average humidity in May
- Average rainfall in May
- Average rainfall days in May
- Average daylight in May
- Average sunshine in May
- Average sunshine days in May
- Average UV index in May
- Average cloud cover in May
- Average visibility in May
Weather in May
Temperature
Portola Valley in May witnesses an average high-temperature of a still enjoyable 64.9°F (18.3°C), indicating a slight variation from April's 62.2°F (16.8°C). Portola Valley records an average low of 50.2°F (10.1°C) throughout the nights in May.Humidity
The average relative humidity in May is 74%.Rainfall
In Portola Valley, California, in May, during 3.8 rainfall days, 0.31" (8mm) of precipitation is typically accumulated. Throughout the year, there are 57.5 rainfall days, and 4.76" (121mm) of precipitation is accumulated.Daylight
The average length of the day in May is 14h and 12min.On the first day of May in Portola Valley, sunrise is at 6:12 am and sunset at 7:59 pm. On the last day of the month, sunrise is at 5:49 am and sunset at 8:23 pm PDT.
Sunshine
The average sunshine in May is 10.7h.UV index
In May, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum UV index of 4 during May translates into these guidelines:
Prioritize safety - Recommendations to avert sunburn are shared. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are May temperatures in Portola Valley?
What is the average humidity in May in Portola Valley?
How much does it rain in Portola Valley in May?
What is the average length of the day in May in Portola Valley?
When are sunrise and sunset in May in Portola Valley?
How many hours of sunshine does Portola Valley have in May?
How high is the UV index in May in Portola Valley?
Average temperature in May
Portola Valley, CA
- Average high temperature in May: 64.9°F
The warmest month (with the highest average high temperature) is August (73°F).
The month with the lowest average high temperature is December (55.8°F).
- Average low temperature in May: 50.2°F
The months with the highest average low temperature are August and September (56.7°F).
The coldest months (with the lowest average low temperature) are January and February (46.4°F).
Average pressure in May
Portola Valley, CA
- Average pressure in May: 29.98"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).
Average wind speed in May
Portola Valley, CA
- Average wind speed in May: 7.5mph
The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is August (5.5mph).
Average humidity in May
Portola Valley, CA
- Average humidity in May: 74%
The month with the highest relative humidity is March (76%).
The month with the lowest relative humidity is October (68%).
Average rainfall in May
Portola Valley, CA
- Average rainfall in May: 0.31"
The wettest month (with the highest rainfall) is February (0.98").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in May
Portola Valley, CA
- Average rainfall days in May: 3.8 days
The month with the highest number of rainy days is March (10.6 days).
The month with the least rainy days is June (0.9 days).
Average daylight in May /
Average sunshine in May
Portola Valley, CA
- Average daylight in May: 14h and 1min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in May: 10h and 4min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in May
Portola Valley, CA
- Average sunshine days in May: 22.9 days
The months with the most sunshine days are June and July (26.3 days).
The month with the least sunshine days is March (18.3 days).
Average UV index in May
Portola Valley, CA
- Average UV index in May: 4
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February, November and December (UV index 3).
Average cloud cover in May
Portola Valley, CA
- Average cloud cover in May: 25
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in May
Portola Valley, CA
- Average visibility in May: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Portola Valley, California, USA
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