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
As Los Altos transitions into September, the average high-temperature stands at a still moderately hot 77.9°F (25.5°C), offering little variation from the preceding month. Los Altos registers a significant reduction from the day's heat, with an average temperature drop to a mild 56.1°F (13.4°C) in September.Humidity
July, September and October, with an average relative humidity of 63%, are the least humid months.Rainfall
In September, in Los Altos, the rain falls for 2.3 days. Throughout September, 0.08" (2mm) of precipitation is accumulated. Throughout the year, in Los Altos, there are 53.1 rainfall days, and 4.41" (112mm) of precipitation is accumulated.Daylight
The average length of the day in September in Los Altos is 12h and 25min.On the first day of September, sunrise is at 6:39 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:52 pm PDT.
Sunshine
In September, the average sunshine in Los Altos is 11h.UV index
The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for ordinary individuals.Note: In September, a daily maximum UV index of 5 leads to the following instructions:
Take heed. Individuals of lighter complexion can be burned in less than half an hour. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures in Los Altos?
What are the least humid months in Los Altos?
What is the average humidity in September in Los Altos?
How many days does it rain in September in Los Altos?
How many hours of daylight does Los Altos have in September?
When are sunrise and sunset in September in Los Altos?
How many hours of sunshine does Los Altos have in September?
How high is the UV index in September in Los Altos?
Average temperature in September
Los Altos, CA
- Average high temperature in September: 77.9°F
The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is December (56.5°F).
- Average low temperature in September: 56.1°F
The month with the highest average low temperature is August (56.8°F).
The coldest month (with the lowest average low temperature) is December (44.1°F).
Average pressure in September
Los Altos, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June and September (29.92"Hg).
Average wind speed in September
Los Altos, CA
- Average wind speed in September: 4.7mph
The windiest months (with the highest average wind speed) are April and May (6.2mph).
The calmest months (with the lowest average wind speed) are August, September, October and November (4.7mph).
Average humidity in September
Los Altos, CA
- Average humidity in September: 63%
The month with the highest relative humidity is March (73%).
The months with the lowest relative humidity are July, September and October (63%).
Average rainfall in September
Los Altos, CA
- Average rainfall in September: 0.08"
The wettest months (with the highest rainfall) are February, March and December (0.83").
The driest months (with the least rainfall) are June, July and August (0.04").
Average rainfall days in September
Los Altos, CA
- Average rainfall days in September: 2.3 days
The month with the highest number of rainy days is March (10 days).
The month with the least rainy days is August (0.4 days).
Average daylight in September /
Average sunshine in September
Los Altos, 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 months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in September
Los Altos, CA
- Average sunshine days in September: 27.5 days
The months with the most sunshine days are July and August (29.8 days).
The month with the least sunshine days is March (19.4 days).
Average UV index in September
Los Altos, 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 February, November and December (UV index 3).
Average cloud cover in September
Los Altos, CA
- Average cloud cover in September: 11
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in September
Los Altos, 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).
Los Altos, California, USA
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