September weather forecast
La Jolla, CA

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Weather in September

The first month of the autumn, September, is also a moderately hot month in La Jolla, California, with an average temperature varying between 64.4°F (18°C) and 78.6°F (25.9°C).

Temperature

August's transformation into September witnesses an average high-temperature of a still moderately hot 78.6°F (25.9°C), noting a minor change from the preceding month. La Jolla witnesses an average low-temperature of 64.4°F (18°C) throughout the month of September.

Humidity

In La Jolla, the average relative humidity in September is 65%.

Rainfall

In La Jolla, during September, the rain falls for 4.2 days and regularly aggregates up to 0.31" (8mm) of precipitation. Throughout the year, there are 57.9 rainfall days, and 7.48" (190mm) of precipitation is accumulated.

Ocean temperature

In La Jolla, in September, the average water temperature is 66.7°F (19.3°C).
Note: The majority of individuals find it unpleasurable to swim in 66.7°F (19.3°C). It becomes progressively harder to manage one's breathing as the water temperature falls below 69.8°F (21°C).

Daylight

In September, the average length of the day is 12h and 22min.
On the first day of the month, sunrise is at 6:24 am and sunset at 7:13 pm. On the last day of September, sunrise is at 6:43 am and sunset at 6:34 pm PDT.

Sunshine

In September, the average sunshine is 10.3h.

UV index

July through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for the ordinary person.
Note: The average daily UV index of 6 in September transforms into the following instructions:
Guard oneself from overexposure. Defence against sun injury is vital. Avoid direct Sun exposure and seek shade from 10 a.m. to 4 p.m., the period of highest UV radiation. Remember, however, that not all shade structures offer full protection. Always opt for UVA and UVB-resistant sunglasses on radiant days.
Updated: Jun 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for La Jolla in September?

In September, the average high-temperature and low-temperature in La Jolla are 78.6°F (25.9°C) and 64.4°F (18°C) respectively.

What is the average humidity in September?

In La Jolla, the average relative humidity in September is 65%.

How much does it rain in September?

In La Jolla, during September, the rain falls for 4.2 days and regularly aggregates up to 0.31" (8mm) of precipitation.

What is the ocean temperature in September?

In La Jolla, the average seawater temperature in September is 66.7°F (19.3°C). For swimming, a surface water temperature of 66.7°F (19.3°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

How many hours of daylight does La Jolla have in September?

In September, the average day length is 12h and 22min.

When are sunrise and sunset in September?

On the first day of September, sunrise is at 6:24 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:43 am and sunset at 6:34 pm PDT.

How long on average sun shines in September?

The average sunshine duration in September is 10.3h.

What are the months with the highest UV index?

July through September, with an average maximum UV index of 6, are months with the highest UV index.

What is the UV index intensity in September?

In September, the average daily maximum UV index is 6. A UV Index estimate of 6 to 7 represents a high health vulnerability 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
La Jolla, CA

Average temperature in September - La Jolla, CA
  • Average high temperature in September: 78.6°F

The warmest month (with the highest average high temperature) is August (79.3°F).
The month with the lowest average high temperature is December (63.5°F).

  • Average low temperature in September: 64.4°F

The month with the highest average low temperature is August (65.8°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).

Average pressure in September
La Jolla, CA

Average pressure in September - La Jolla, CA
  • Average pressure in September: 29.88"Hg

The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are June and September (29.88"Hg).

Average wind speed in September
La Jolla, CA

Average wind speed in September - La Jolla, CA
  • Average wind speed in September: 5mph

The windiest month (with the highest average wind speed) is April (6mph).
The calmest month (with the lowest average wind speed) is October (4.8mph).

Average humidity in September
La Jolla, CA

Average humidity in September - La Jolla, CA
  • Average humidity in September: 65%

The months with the highest relative humidity are May and June (71%).
The month with the lowest relative humidity is November (57%).

Average rainfall in September
La Jolla, CA

Average rainfall in September - La Jolla, CA
  • Average rainfall in September: 0.31"

The wettest month (with the highest rainfall) is February (1.46").
The driest month (with the least rainfall) is June (0.12").

Average rainfall days in September
La Jolla, CA

Average rainfall days in September - La Jolla, CA
  • Average rainfall days in September: 4.2 days

The month with the highest number of rainy days is March (7.1 days).
The month with the least rainy days is June (2.2 days).

Average sea temperature in September
La Jolla, CA

Average sea temperature in September - La Jolla, CA
  • Average sea temperature in September: 66.7°F

The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (58.7°F).

Average daylight in September /
Average sunshine in September
La Jolla, CA

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

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

  • Average sunshine in September: 10h and 2min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 48min).

Average sunshine days in September
La Jolla, CA

Average sunshine days in September - La Jolla, CA
  • Average sunshine days in September: 22.4 days

The month with the most sunshine days is January (24.8 days).
The month with the least sunshine days is February (20.2 days).

Average UV index in September
La Jolla, CA

Average UV index in September - La Jolla, CA
  • Average UV index in September: 6

The months with the highest UV index are July, August and September (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 4).

Average cloud cover in September
La Jolla, CA

Average cloud cover in September - La Jolla, CA
  • Average cloud cover in September: 11

The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 8).

Average visibility in September
La Jolla, CA

Average visibility in September - La Jolla, 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).

La Jolla, California, USA

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