Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The average high-temperature during September registers at a still warm 79°F (26.1°C), closely corresponding to the preceding month. Castro Valley logs a notable disparity from the daily highs during September, as the nighttime temperature lowers to an average of 56.3°F (13.5°C).Humidity
The least humid month is September, with an average relative humidity of 61%.Rainfall
In Castro Valley, in September, it is raining for 2.1 days, with typically 0.12" (3mm) of accumulated precipitation. Throughout the year, in Castro Valley, California, there are 69.2 rainfall days, and 11.1" (282mm) of precipitation is accumulated.Daylight
In Castro Valley, the average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:39 am and sunset at 7:36 pm. On the last day of September, in Castro Valley, California, sunrise is at 7:03 am and sunset at 6:52 pm PDT.
Sunshine
In September, the average sunshine is 11.1h.UV index
In Castro Valley, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, a regular UV index of 5 translates into these guidelines:
Prioritize safety - Recommendations to avert sunburn are shared. Considering the harmful UV rays from the Sun during midday, it's essential to reduce exposure. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Castro Valley in September?
What is the least humid month in Castro Valley?
What is the average humidity in September in Castro Valley?
How much does it rain in Castro Valley in September?
What is the average length of the day in September in Castro Valley?
When are sunrise and sunset in September in Castro Valley?
How long on average sun shines in September in Castro Valley?
What is the UV index intensity in September in Castro Valley?
Average temperature in September
Castro Valley, CA
- Average high temperature in September: 79°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (55.9°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is August (56.5°F).
The coldest months (with the lowest average low temperature) are January and December (43.7°F).
Average pressure in September
Castro Valley, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
Castro Valley, CA
- Average wind speed in September: 5mph
The windiest month (with the highest average wind speed) is May (6.6mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).
Average humidity in September
Castro Valley, CA
- Average humidity in September: 61%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (61%).
Average rainfall in September
Castro Valley, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (2.28").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Castro Valley, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is August (0.9 days).
Average daylight in September /
Average sunshine in September
Castro Valley, CA
- Average daylight in September: 12h and 2min
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 September: 11h and 1min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in September
Castro Valley, CA
- Average sunshine days in September: 27.1 days
The month with the most sunshine days is August (28.9 days).
The month with the least sunshine days is March (17.3 days).
Average UV index in September
Castro Valley, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Castro Valley, CA
- Average cloud cover in September: 10
The months with the most cloud cover are March and December (Cloud cover 34).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in September
Castro Valley, CA
- Average visibility in September: 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).
Castro Valley, California, USA
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