September weather forecastSan Clemente, CA
September
Weather in September
September, the first month of the autumn in San Clemente, is still a warm month, with temperature in the range of an average low of 63.5°F (17.5°C) and an average high of 77.4°F (25.2°C).Temperature
September stands out as San Clemente's warmest month, with an average high-temperature of 77.4°F (25.2°C) and a low-temperature of 63.5°F (17.5°C).Humidity
In September, the average relative humidity is 68%.Rainfall
In San Clemente, in September, during 3.3 rainfall days, 0.12" (3mm) of precipitation is typically accumulated. In San Clemente, during the entire year, the rain falls for 51.1 days and collects up to 3.66" (93mm) of precipitation.Ocean temperature
In San Clemente, in September, the average water temperature is 67.1°F (19.5°C).Note: For most, swimming in 67.1°F (19.5°C) is not a pleasant experience. As the temperature falls from 69.8°F (21°C) to 59°F (15°C), controlling one's breathing becomes more difficult.
Daylight
The average length of the day in September in San Clemente is 12h and 22min.On the first day of September, sunrise is at 6:25 am and sunset at 7:15 pm. On the last day of the month, sunrise is at 6:44 am and sunset at 6:35 pm PDT.
Sunshine
In September, the average sunshine is 10.2h.UV index
The months with the highest UV index in San Clemente are July through September, with an average maximum UV index of 6. A UV Index reading of 6 to 7 represents a high health vulnerability from exposure to the Sun's UV radiation for the ordinary person.Note: The maximum UV index of 6 during September leads to these instructions:
Persist with precautions and heed sun safety advice. Prevention of sunburn is compulsory. 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. Employ a wide-brim hat for potent defense against up to 50% of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Clemente, CA
- Average high temperature in September: 77.4°F
The warmest month (with the highest average high temperature) is September (77.4°F).
The month with the lowest average high temperature is December (62.6°F).
- Average low temperature in September: 63.5°F
The months with the highest average low temperature are August and September (63.5°F).
The coldest month (with the lowest average low temperature) is February (49.6°F).
Average pressure in September
San Clemente, CA
- Average pressure in September: 29.89"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
San Clemente, CA
- Average wind speed in September: 4.9mph
The windiest month (with the highest average wind speed) is April (6.2mph).
The calmest months (with the lowest average wind speed) are August and September (4.9mph).
Average humidity in September
San Clemente, CA
- Average humidity in September: 68%
The month with the highest relative humidity is June (75%).
The month with the lowest relative humidity is November (60%).
Average rainfall in September
San Clemente, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is December (0.71").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in September
San Clemente, CA
- Average rainfall days in September: 3.3 days
The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is June (1.4 days).
Average sea temperature in September
San Clemente, CA
- Average sea temperature in September: 67.1°F
The best month for swimming (with the highest average sea temperature) is August (68.3°F).
The coldest months (with the lowest average sea temperature) are January and February (58.9°F).
Average daylight in September /
Average sunshine in September
San Clemente, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in September: 10h and 12min
The months with the most sunshine are July and August (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 6h and 30min).
Average sunshine days in September
San Clemente, CA
- Average sunshine days in September: 23.8 days
The month with the most sunshine days is October (26 days).
The month with the least sunshine days is February (21.6 days).
Average UV index in September
San Clemente, CA
- Average UV index in September: 6
The months with the highest UV index are July, August and September (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 4).
Average cloud cover in September
San Clemente, CA
- Average cloud cover in September: 15
The months with the most cloud cover are March and May (Cloud cover 27).
The month with the least cloud cover is August (Cloud cover 11).
Average visibility in September
San Clemente, 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).
