September weather forecastHayward, CA
September
Weather in September
September transitions Hayward from the hot summers to the cooler fall season. Although the rain does not show a significant increase, the temperatures start their descent into cooler hues, and the humidity decreases slightly. A decrease in daylight hours propounds a slight decline in sunshine hours too. The winds in September decrease slightly, with an average speed of 5mph (8km/h), indicating calm and enjoyable weather. Even though temperatures remain high, September marks the beginning of the shift into the colder months.Temperature
Hayward, California, marks the start of September with an average high-temperature of a still moderately hot 79°F (26.1°C), hinting at a slight fluctuation from August's 79.7°F (26.5°C). September presents a pronounced difference from daytime highs, with a consistent average low-temperature of 56.3°F (13.5°C).Humidity
The least humid month is September, with an average relative humidity of 61%.Rainfall
In Hayward, in September, it is raining for 2.1 days, with typically 0.12" (3mm) of accumulated precipitation. In Hayward, during the entire year, the rain falls for 69.2 days and collects up to 11.1" (282mm) of precipitation.Daylight
In Hayward, the average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:39 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:52 pm PDT.
Sunshine
The average sunshine in September is 11.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for ordinary individuals.Note: The average daily UV index of 5 in September transforms into the following instructions:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Hayward, CA
- Average high temperature in September: 79°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (55.9°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is August (56.5°F).
The coldest months (with the lowest average low temperature) are January and December (43.7°F).
Average pressure in September
Hayward, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).
Average wind speed in September
Hayward, CA
- Average wind speed in September: 5mph
The windiest month (with the highest average wind speed) is May (6.6mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).
Average humidity in September
Hayward, CA
- Average humidity in September: 61%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (61%).
Average rainfall in September
Hayward, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (2.28").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Hayward, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is August (0.9 days).
Average daylight in September /
Average sunshine in September
Hayward, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 6min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days in September
Hayward, CA
- Average sunshine days in September: 27.1 days
The month with the most sunshine days is August (28.9 days).
The month with the least sunshine days is March (17.3 days).
Average UV index in September
Hayward, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Hayward, CA
- Average cloud cover in September: 10
The months with the most cloud cover are March and December (Cloud cover 34).
The month with the least cloud cover is July (Cloud cover 7).
Average visibility in September
Hayward, 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).
