September weather forecast and climate
Placentia, CA

Weather in September

September, the first month of the autumn, in Placentia, is also a moderately hot month, with temperature in the range of an average low of 64.8°F (18.2°C) and an average high of 84°F (28.9°C).

Temperature

In Placentia, the average high-temperature is relatively the same as in August - a still warm 84°F (28.9°C). The average low-temperature, in Placentia, is 64.8°F (18.2°C).

Heat index

In September, the average heat index is calculated to a tropical 86.5°F (30.3°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like', 'real feel', 'felt air temperature', or 'apparent temperature', combines air temperature and relative humidity to represent a human perceived temperature equivalent. Additional factors like activity, pregnancy, wind, and clothing affect individual temperature impact. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

The average relative humidity in Placentia is 56%.

Rainfall

In Placentia, in September, it is raining for 3 days, with typically 0.16" (4mm) of accumulated precipitation. In Placentia, during the entire year, the rain falls for 53.2 days and collects up to 7.72" (196mm) of precipitation.

Daylight

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

Sunshine

The average sunshine is 10.7h.

UV index

June 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 the exposure to the Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. 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.
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FAQ

What is the temperature in September in Placentia?

In Placentia, California, in September, the average high-temperature is 84°F (28.9°C), and the average low-temperature is 64.8°F (18.2°C). The average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), that calculates temperature value influenced by the moisture in the air, in September is calculated to 86.5°F (30.3°C).

What is the average humidity in September in Placentia?

The average relative humidity in September is 56%.

How many days does it rain in September in Placentia?

In Placentia, in September, during 3 rainfall days, 0.16" (4mm) of precipitation is typically accumulated.

How many hours of daylight does Placentia have in September?

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

How long on average sun shines in September in Placentia?

In September, the average sunshine is 10.7h.

What is the month with the highest UV index in Placentia?

Months with the highest UV index in Placentia, California, are June through September, with an average maximum UV index of 6.

What is the UV index reading in September in Placentia?

In Placentia, California, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from the exposure to the Sun's UV rays.

Average temperature in September
Placentia, CA

Average temperature in September - Placentia, CA
  • Average high temperature in September: 84°F

The warmest month (with the highest average high temperature) is August (85.3°F).
The month with the lowest average high temperature is December (64.2°F).

  • Average low temperature in September: 64.8°F

The month with the highest average low temperature is August (65.7°F).
The coldest month (with the lowest average low temperature) is February (49.6°F).

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Average pressure in September
Placentia, CA

Average pressure in September - Placentia, CA
  • Average pressure in September: 29.89"

The month with the highest atmospheric pressure is January (30.1").
The month with the lowest atmospheric pressure is June (29.88").

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Average wind speed in September
Placentia, CA

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

The windiest month (with the highest average wind speed) is April (5.8mph).
The calmest month (with the lowest average wind speed) is September (4.5mph).

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Average humidity in September
Placentia, CA

Average humidity in September - Placentia, CA
  • Average humidity in September: 56%

The month with the highest relative humidity is June (63%).
The month with the lowest relative humidity is November (50%).

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Average rainfall in September
Placentia, CA

Average rainfall in September - Placentia, CA
  • Average rainfall in September: 0.16"

The wettest month (with the highest rainfall) is December (1.65").
The driest month (with the least rainfall) is June (0.04").

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Average rainfall days in September
Placentia, CA

Average rainfall days in September - Placentia, CA
  • Average rainfall days in September: 3 days

The month with the highest number of rainy days is March (7.4 days).
The month with the least rainy days is June (1.4 days).

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Average daylight in September /
Average sunshine in September
Placentia, CA

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

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

  • Average sunshine in September: 10.7h

The month with the most sunshine is July (Average sunshine: 12.1h).
Months with the least sunshine are February and December (Average sunshine: 6.8).

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Average sunshine days in September
Placentia, CA

Average sunshine days in September - Placentia, CA
  • Average sunshine days in September: 24.4 days

The month with the most sunshine days is August (26.7 days).
The month with the least sunshine days is February (20.7 days).

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Average UV index in September
Placentia, CA

Average UV index in September - Placentia, CA
  • Average UV index in September: 6

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

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Average cloud cover in September
Placentia, CA

Average cloud cover in September - Placentia, CA
  • Average cloud cover in September: 8

Months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 5).

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Average visibility in September
Placentia, CA

Average visibility in September - Placentia, CA
  • Average visibility in September: 6mi

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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