September weather forecastNorwalk, CA
September
Weather in September
September marks the advent of fall in Norwalk, with temperatures beginning to recede from the summer's peak. The average high temperature dips to 82.2°F (27.9°C), a slight decrease from August, indicating the start of the transitional period to winter. However, despite the temperature drop, September continues to display summer-like weather with ample sunshine and minimal rainfall. This month retains the beautiful weather of summer, while slowly introducing the chills of autumn. The blend of warm days and cooler nights characterizes the pleasant September weather.Temperature
The arrival of September sees an average high-temperature of a still moderately hot 82.2°F (27.9°C), hardly diverging from August's 83.1°F (28.4°C). September nights experience a consistent temperature drop to a comfortable 64.9°F (18.3°C).Heat index
September's mean heat index is evaluated at 84.2°F (29°C). If exposure and activity are sustained, they might cause a feeling of weariness, resulting in heat cramps.In the scope of the heat index, its values resonate with shade and light wind conditions. Heat index values may be hiked up by 15 Fahrenheit (8 Celsius) degrees under direct sunshine.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is an estimation of the warmth sensation when considering humidity levels. Factors including metabolic differences, physical activity, and clothing are additional elements that influence the individual's temperature experience. When you're directly under the sun's rays, remember that the heat index may surge by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Youngsters are usually more at risk than adults, considering they sweat less. Additionally, their high skin surface area compared to their little bodies and their high heat production due to activity increases their risk.
Humidity
In September, the average relative humidity is 58%.Rainfall
In Norwalk, in September, during 3 rainfall days, 0.16" (4mm) of precipitation is typically accumulated. In Norwalk, during the entire year, the rain falls for 49.5 days and collects up to 7.05" (179mm) of precipitation.Daylight
The average length of the day in September in Norwalk, California, is 12h and 22min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:17 pm. On the last day of September, sunrise is at 6:46 am and sunset at 6:37 pm PDT.
Sunshine
The average sunshine in September is 10.6h.UV index
The months with the highest UV index are June through September, with an average maximum UV index of 6. A UV Index estimate of 6 to 7 represents a high threat to health from exposure to the Sun's UV rays for average individuals.Note: The maximum daily UV index, 6 in September, converts into the following recommendations:
Escape overexposure. People with light skin may incur burns in fewer than 20 minutes. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Norwalk, CA
- Average high temperature in September: 82.2°F
The warmest month (with the highest average high temperature) is August (83.1°F).
The month with the lowest average high temperature is December (64.6°F).
- Average low temperature in September: 64.9°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 (50.5°F).
Average pressure in September
Norwalk, 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
Norwalk, CA
- Average wind speed in September: 4.8mph
The windiest month (with the highest average wind speed) is April (6.1mph).
The calmest month (with the lowest average wind speed) is October (4.7mph).
Average humidity in September
Norwalk, CA
- Average humidity in September: 58%
The month with the highest relative humidity is June (66%).
The month with the lowest relative humidity is November (51%).
Average rainfall in September
Norwalk, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is December (1.46").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
Norwalk, CA
- Average rainfall days in September: 3 days
The month with the highest number of rainy days is March (7.1 days).
The month with the least rainy days is June (1.2 days).
Average daylight in September /
Average sunshine in September
Norwalk, CA
- Average daylight in September: 12h and 24min
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 36min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in September
Norwalk, CA
- Average sunshine days in September: 23.5 days
The months with the most sunshine days are January and August (25.6 days).
The month with the least sunshine days is February (21.1 days).
Average UV index in September
Norwalk, 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
Norwalk, 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
Norwalk, 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).
