September weather forecastSan Marino, CA
September
Weather in September
The first month of the autumn, September, is still a warm month in San Marino, California, with an average temperature fluctuating between 63.5°F (17.5°C) and 84.7°F (29.3°C).Temperature
September ushers in an average high-temperature of a moderately hot 84.7°F (29.3°C), aligning closely with the preceding month. Throughout the month of September, the nighttime temperature dips to an average of 63.5°F (17.5°C).Heat index
The heat index for September is computed to be a tropical 86°F (30°C). Uninterrupted exposure and activity might result in fatigue, potentially causing heat cramps.Realize that the values for the heat index are set for shaded places and light winds. Direct sunlight can potentially boost the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'feels like', is achieved by amalgamating air temperature with the relative humidity readings. The effect is personal, with varied weather perceptions among individuals due to differences in body mass, stature, and physical activity. Being aware that direct sunlight can impact the felt heat might mean an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Young individuals usually face greater risks than adults as their sweat production is less. Also, their larger skin surface relative to their small bodies and the high heat generation due to their activity contributes to their vulnerability.
Humidity
In San Marino, the average relative humidity in September is 51%.Rainfall
In September, the rain falls for 2.8 days. Throughout September, 0.16" (4mm) of precipitation is accumulated. Throughout the year, there are 45 rainfall days, and 6.61" (168mm) of precipitation is accumulated.Daylight
In San Marino, 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
In September, the average sunshine in San Marino is 10.7h.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 radiation for average individuals.Note: A daily high UV index of 6 in September leads to these guidelines:
Employ safeguards and advocate sun safety protocols. Shielding against skin and eye damage is crucial. UV radiation from the sun is at its strongest between 10 a.m. and 4 p.m. Try to limit direct exposure during these hours. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Marino, CA
- Average high temperature in September: 84.7°F
The warmest month (with the highest average high temperature) is August (87.1°F).
The month with the lowest average high temperature is December (63.1°F).
- Average low temperature in September: 63.5°F
The month with the highest average low temperature is August (64.8°F).
The coldest month (with the lowest average low temperature) is February (47.1°F).
Average pressure in September
San Marino, CA
- Average pressure in September: 29.89"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
San Marino, CA
- Average wind speed in September: 4.4mph
The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest month (with the lowest average wind speed) is September (4.4mph).
Average humidity in September
San Marino, CA
- Average humidity in September: 51%
The month with the highest relative humidity is June (59%).
The month with the lowest relative humidity is November (47%).
Average rainfall in September
San Marino, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is December (1.34").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
San Marino, CA
- Average rainfall days in September: 2.8 days
The month with the highest number of rainy days is March (5.8 days).
The month with the least rainy days is June (1.2 days).
Average daylight in September /
Average sunshine in September
San Marino, 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 42min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 54min).
Average sunshine days in September
San Marino, CA
- Average sunshine days in September: 25 days
The month with the most sunshine days is June (27.1 days).
The month with the least sunshine days is February (22.3 days).
Average UV index in September
San Marino, 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 January, February, November and December (UV index 4).
Average cloud cover in September
San Marino, CA
- Average cloud cover in September: 7
The months with the most cloud cover are March and December (Cloud cover 21).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility in September
San Marino, 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).
