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
The transition into September reveals an average high-temperature of a still moderately hot 82.6°F (28.1°C), mirroring a close resemblance to August. The low-temperature average for Downey during September stands at a refreshing 64.9°F (18.3°C).Heat index
The average heat index in September is computed to be 84.2°F (29°C). Prolonged activity during exposure might result in a state of fatigue and cause heat cramps.It is essential to grasp that the heat index's numbers are for shade and light wind settings. Heat index values may rise by up to 15 Fahrenheit (8 Celsius) degrees when exposed to direct sunlight.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. A person's impression of weather can be shaped by many aspects, among them metabolic variations, pregnancy, and levels of physical activity. Consider the fact that direct sun exposure can influence how hot one feels, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to babies and toddlers. Young ones often disregard the necessity to rest and hydrate. Thirst usually indicates advanced dehydration - hence, it is key to stay hydrated, particularly during ongoing physical activities.
Humidity
In September, the average relative humidity is 57%.Rainfall
In Downey, during September, the rain falls for 2.8 days and regularly aggregates up to 0.16" (4mm) of precipitation. Throughout the year, there are 46 rainfall days, and 6.77" (172mm) of precipitation is accumulated.Daylight
In Downey, the average length of the day in September is 12h and 22min.On the first day of September, sunrise is at 6:26 am and sunset at 7:17 pm. On the last day of the month, sunrise is at 6:46 am and sunset at 6:37 pm PDT.
Sunshine
The average sunshine in September in Downey is 10.6h.UV index
June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: In September, the UV index of 6 transforms into the following advice:
Continue precautions and advocate sun safety advice. Deterrence of sunburn is indispensable. It's important to stay in the shade and limit exposure to the sun from 10 a.m. to 4 p.m., when UV radiation is most intense, although remember that shade structures may not provide full sun protection. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How hot is it in September?
What is the average humidity in September?
How much does it rain in September?
How many hours of daylight does Downey have in September?
When are sunrise and sunset in September in Downey?
How many hours of sunshine does Downey have in September?
When is the highest UV index?
How high is the UV index in September?
Average temperature in September
Downey, CA
- Average high temperature in September: 82.6°F
The warmest month (with the highest average high temperature) is August (84°F).
The month with the lowest average high temperature is December (64.9°F).
- Average low temperature in September: 64.9°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 (50.5°F).
Average pressure in September
Downey, CA
- Average pressure in September: 29.89"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are June and September (29.89"Hg).
Average wind speed in September
Downey, CA
- Average wind speed in September: 4.7mph
The windiest month (with the highest average wind speed) is April (6.1mph).
The calmest months (with the lowest average wind speed) are September and October (4.7mph).
Average humidity in September
Downey, CA
- Average humidity in September: 57%
The month with the highest relative humidity is June (65%).
The month with the lowest relative humidity is November (51%).
Average rainfall in September
Downey, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is December (1.42").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
Downey, CA
- Average rainfall days in September: 2.8 days
The month with the highest number of rainy days is March (6.8 days).
The month with the least rainy days is June (1.3 days).
Average daylight in September /
Average sunshine in September
Downey, 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 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 48min).
Average sunshine days in September
Downey, CA
- Average sunshine days in September: 24.2 days
The month with the most sunshine days is August (26.3 days).
The month with the least sunshine days is February (22.2 days).
Average UV index in September
Downey, CA
- Average UV index in September: 6
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are February, November and December (UV index 4).
Average cloud cover in September
Downey, CA
- Average cloud cover in September: 9
The months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 6).
Average visibility in September
Downey, 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).
Downey, California, USA
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