Long Beach
California, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Long Beach, CA

A stunning shot of a colorful sunset sky over the Pacific Ocean in Long Beach, California, and views of distant city buildings, calm water, and soft sand
A stunning shot of a colorful sunset sky over the Pacific Ocean in Long Beach, California, and views of distant city buildings, calm water, and soft sand
September, the first month of the autumn, in Long Beach, is still a warm month, with average temperature fluctuating between 82°F (27.8°C) and 63.1°F (17.3°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a still moderately hot 82°F (27.8°C). In Long Beach, California, in September, the average low-temperature is 63.1°F (17.3°C).

Heat index

In September, the average heat index is estimated at a hot 86.4°F (30.2°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'felt air temperature', 'feels like', or 'apparent temperature', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like wind, pregnancy, clothing, and activity influence one's weather impression. Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.

Humidity

In Long Beach, California, the average relative humidity in September is 69.2%.

Rainfall

In September, in Long Beach, the rain falls for 0.9 days. Throughout September, 0.2" (4mm) of precipitation is accumulated. Throughout the year, there are 35.2 rainfall days, and 10.2" (259mm) of precipitation is accumulated.

Ocean temperature

In September, the average ocean temperature in Long Beach is 66.7°F (19.3°C).
Note: Swimming in 66.7°F (19.3°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

Daylight

In September, the average length of the day in Long Beach is 12.4h.

Sunshine

In September, the average sunshine in Long Beach, California, is 9h.

UV index

The average daily maximum UV index is 8. A UV Index estimate of 8 to 10 represents a very high health risk from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: In September, the average maximum UV index of 8 translate into the following recommendations:
Take extra precautions. Fair-skinned individuals may get burned in less than 10 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in Long Beach?

In September, in Long Beach, California, the average high-temperature is 82°F (27.8°C), and the average low-temperature is 63.1°F (17.3°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), that combines relative humidity and air temperature, in September is estimated at 86.4°F (30.2°C).

What is the average humidity in September in Long Beach?

In Long Beach, California, the average relative humidity in September is 69.2%.

How many days does it rain in September in Long Beach?

In Long Beach, during September, the rain falls for 0.9 days and regularly aggregates up to 0.2" (4mm) of precipitation.

How cold is the water in September in Long Beach?

In Long Beach, 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).

What is the average length of the day in September in Long Beach?

In Long Beach, California, the average length of the day in September is 12.4h.

How many hours of sunshine does Long Beach have in September?

In September, the average sunshine in Long Beach, California, is 9h.

What is the UV index intensity in September in Long Beach?

In September, the average daily maximum UV index in Long Beach is 8. A UV Index estimate of 8 to 10 represents a very high health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Long Beach, CA
  • Average high temperature in September: 82.1°F

The warmest month (with the highest average high temperature) is August (83.8°F).
The month with the lowest average high temperature is December (66.8°F).

  • Average low temperature in September: 63.2°F

The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is December (45.8°F).

Average humidity in September - Long Beach, CA
  • Average humidity in September: 69.2%

The month with the highest relative humidity is June (69.6%).
The month with the lowest relative humidity is January (64.7%).

Average rainfall in September - Long Beach, CA
  • Average rainfall in September: 0.2"

The wettest month (with the highest rainfall) is January (2.3").
Driest months (with the lowest rainfall) are June, July and August (0").

Average rainfall days in September - Long Beach, CA
  • Average rainfall days in September: 0.9 days

The month with the highest number of rainy days is February (6.5 days).
The month with the lowest number of rainy days is August (0.3 days).

Average sea temperature in September - Long Beach, CA
  • Average sea temperature in September: 66.7°F

Best months for swimming (with the highest average sea temperature) are July and August (67.9°F).
The coldest month (with the lowest average sea temperature) is January (58.3°F).

Average daylight in September / Average sunshine in September - Long Beach, CA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.4h).
The month with shortest days is December (Average daylight: 9.9h).

  • Average sunshine in September: 9h

Months with most sunshine are July and August (Average sunshine: 11h).
Months with least sunshine are January, November and December (Average sunshine: 7).

Average UV index in September - Long Beach, CA
  • Average UV index in September: 8

Months with the highest UV index are June, July and August (UV index 10).
Months with the lowest UV index are January and December (UV index 3).