September weather forecast
Simi Valley, CA

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The Simi Valley city in California, with a view of the scenic Rocky Peak and hilly ranges
The Simi Valley city in California, with a view of the scenic Rocky Peak and hilly ranges

Weather in September

September, the first month of the autumn in Simi Valley, is still a warm month, with temperature in the range of an average low of 62.1°F (16.7°C) and an average high of 79.7°F (26.5°C).

Temperature

During September, the average high-temperature is a still warm 79.7°F (26.5°C), maintaining a close resemblance to that of the preceding month. The average temperature drops to an enjoyable 62.1°F (16.7°C) during the night in the month of September.

Humidity

In Simi Valley, the average relative humidity in September is 55%.

Rainfall

In Simi Valley, California, during September, the rain falls for 2.7 days and regularly aggregates up to 0.2" (5mm) of precipitation. In Simi Valley, California, during the entire year, the rain falls for 53.7 days and collects up to 9.61" (244mm) of precipitation.

Daylight

In September, the average length of the day is 12h and 22min.
On the first day of the month, sunrise is at 6:29 am and sunset at 7:20 pm. On the last day of September, in Simi Valley, sunrise is at 6:49 am and sunset at 6:40 pm PDT.

Sunshine

In September, the average sunshine is 10.9h.

UV index

In Simi Valley, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.
Note: In September, an average UV index of 5 transforms into the following instructions:
Adopt protective measures - It is advised to guard against sun damage. Around midday, solar radiation is most harmful; hence, exposure should be limited. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat.
Updated: Aug 25, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the temperature in September?

During September, Simi Valley experiences an average high-temperature of 79.7°F (26.5°C) and a low-temperature of 62.1°F (16.7°C). The average heat index (a.k.a. 'real feel', 'feels like'), which represents the influence of relative humidity on air temperature, in August is calculated to be 84.2°F (29°C).

What is the average humidity in September?

In Simi Valley, California, the average relative humidity in September is 55%.

How many days does it rain in September?

In Simi Valley, in September, it is raining for 2.7 days, with typically 0.2" (5mm) of accumulated precipitation.

What is the average length of the day in September?

The average day length in September is 12h and 22min.

What time are sunrise and sunset in September?

In September, on the first day of the month, sunrise is at 6:29 am and sunset at 7:20 pm. On the last day of the month, sunrise is at 6:49 am and sunset at 6:40 pm PDT.

How long on average sun shines in September?

In September, the average sunshine duration is 10.9h.

How high is the UV index in September?

In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a medium health risk from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Simi Valley, CA

Average temperature in September - Simi Valley, CA
  • Average high temperature in September: 79.7°F

The warmest month (with the highest average high temperature) is August (82.2°F).
The month with the lowest average high temperature is December (60.1°F).

  • Average low temperature in September: 62.1°F

The month with the highest average low temperature is August (63.1°F).
The coldest month (with the lowest average low temperature) is December (46.4°F).

Average pressure in September
Simi Valley, CA

Average pressure in September - Simi Valley, CA
  • Average pressure in September: 29.9"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are June and September (29.9"Hg).

Average wind speed in September
Simi Valley, CA

Average wind speed in September - Simi Valley, CA
  • Average wind speed in September: 4.5mph

The windiest month (with the highest average wind speed) is December (6.5mph).
The calmest month (with the lowest average wind speed) is August (4.3mph).

Average humidity in September
Simi Valley, CA

Average humidity in September - Simi Valley, CA
  • Average humidity in September: 55%

The month with the highest relative humidity is June (62%).
The month with the lowest relative humidity is November (50%).

Average rainfall in September
Simi Valley, CA

Average rainfall in September - Simi Valley, CA
  • Average rainfall in September: 0.2"

The wettest month (with the highest rainfall) is February (1.93").
The driest month (with the least rainfall) is June (0.08").

Average rainfall days in September
Simi Valley, CA

Average rainfall days in September - Simi Valley, CA
  • Average rainfall days in September: 2.7 days

The month with the highest number of rainy days is March (8 days).
The months with the least rainy days are June and August (1.5 days).

Average daylight in September /
Average sunshine in September
Simi Valley, CA

Average daylight in September / Average sunshine in September - Simi Valley, CA
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).

  • Average sunshine in September: 10h and 5min

The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 48min).

Average sunshine days in September
Simi Valley, CA

Average sunshine days in September - Simi Valley, CA
  • Average sunshine days in September: 23.5 days

The month with the most sunshine days is August (25.4 days).
The month with the least sunshine days is February (20.9 days).

Average UV index in September
Simi Valley, CA

Average UV index in September - Simi Valley, CA
  • Average UV index in September: 5

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 3).

Average cloud cover in September
Simi Valley, CA

Average cloud cover in September - Simi Valley, CA
  • Average cloud cover in September: 7

The month with the most cloud cover is March (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 5).

Average visibility in September
Simi Valley, CA

Average visibility in September - Simi 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).

Simi Valley, California, USA

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