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 sea temperature 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
In Redwood City, September's average high-temperature stands at a still agreeable 72.7°F (22.6°C), closely related to the preceding month. During the month of September, Redwood City's nighttime temperature lowers to an average of 56.7°F (13.7°C).Humidity
In September, the average relative humidity is 69%.Rainfall
In Redwood City, during September, the rain falls for 2.4 days and regularly aggregates up to 0.12" (3mm) of precipitation. In Redwood City, during the entire year, the rain falls for 73.4 days and collects up to 11.89" (302mm) of precipitation.Ocean temperature
The months with the warmest seawater in Redwood City are August and September, with an average ocean temperature of 57.7°F (14.3°C).Note: It is advised against swimming in 57.7°F (14.3°C) when it drops below 50°F (10°C). Such temperatures can cause extreme cold shock, leading to hyperventilation.
Daylight
The average length of the day in September is 12h and 25min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:37 pm. On the last day of September, in Redwood City, sunrise is at 7:04 am and sunset at 6:53 pm PDT.
Sunshine
In September, the average sunshine is 11h.UV index
The months with the highest UV index are June through September, with an average maximum UV index of 5. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.Note: The maximum daily UV index of 5 during September translates into the following directions:
Make use of precautions - Suggestions to resist sunburn are communicated. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
How many days does it rain in September?
What are the months with the warmest ocean?
How cold is the water in September?
How many hours of daylight does Redwood City have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Redwood City have in September?
What is the month with the highest UV index?
What is the UV index reading in September?
Average temperature in September
Redwood City, CA
- Average high temperature in September: 72.7°F
The warmest months (with the highest average high temperature) are July and August (73°F).
The month with the lowest average high temperature is December (55.9°F).
- Average low temperature in September: 56.7°F
The month with the highest average low temperature is September (56.7°F).
The coldest month (with the lowest average low temperature) is February (46°F).
Average pressure in September
Redwood City, CA
- Average pressure in September: 29.92"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 September
Redwood City, CA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is April (7.5mph).
The calmest months (with the lowest average wind speed) are August, September and October (5.5mph).
Average humidity in September
Redwood City, CA
- Average humidity in September: 69%
The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is October (68%).
Average rainfall in September
Redwood City, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (2.36").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Redwood City, CA
- Average rainfall days in September: 2.4 days
The month with the highest number of rainy days is March (12.8 days).
The month with the least rainy days is August (0.8 days).
Average sea temperature in September
Redwood City, CA
- Average sea temperature in September: 57.7°F
The best months for swimming (with the highest average sea temperature) are August and September (57.7°F).
The coldest month (with the lowest average sea temperature) is April (53.4°F).
Average daylight in September /
Average sunshine in September
Redwood City, 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 0min
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 48min).
Average sunshine days in September
Redwood City, CA
- Average sunshine days in September: 26.4 days
The month with the most sunshine days is August (27.6 days).
The month with the least sunshine days is March (17.5 days).
Average UV index in September
Redwood City, CA
- Average UV index in September: 5
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are November and December (UV index 3).
Average cloud cover in September
Redwood City, CA
- Average cloud cover in September: 12
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 September
Redwood City, 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).
Redwood City, California, USA
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