September weather forecastSan Ysidro, CA
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in San Ysidro, California, with an average temperature varying between 80.1°F (26.7°C) and 65.5°F (18.6°C).Temperature
A minimal variation is noted in San Ysidro's average high-temperature at the onset of September, reaching a still moderately hot 80.1°F (26.7°C) from August's 81.1°F (27.3°C). Throughout September, San Ysidro witnesses a consistent average low-temperature of 65.5°F (18.6°C).Humidity
In September, the average relative humidity is 62%.Rainfall
In September, the rain falls for 4.5 days. Throughout September, 0.35" (9mm) of precipitation is accumulated. Throughout the year, there are 57.8 rainfall days, and 7.28" (185mm) of precipitation is accumulated.Daylight
The average length of the day in September is 12h and 21min.On the first day of the month, sunrise is at 6:23 am and sunset at 7:12 pm. On the last day of September, sunrise is at 6:42 am and sunset at 6:33 pm PDT.
Sunshine
In San Ysidro, the average sunshine in September is 10.2h.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 health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the maximum UV index of 6 suggests this advice:
Resist extreme sun exposure. Guarding against solar damage is essential. Between 10 a.m. and 4 p.m., the Sun emits the most powerful UV radiation. Limit direct exposure to the Sun during these hours. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
San Ysidro, CA
- Average high temperature in September: 80.1°F
The warmest month (with the highest average high temperature) is August (81.1°F).
The month with the lowest average high temperature is December (64°F).
- Average low temperature in September: 65.5°F
The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).
Average pressure in September
San Ysidro, CA
- Average pressure in September: 29.88"Hg
The month with the highest atmospheric pressure is January (30.08"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.88"Hg).
Average wind speed in September
San Ysidro, CA
- Average wind speed in September: 5mph
The windiest months (with the highest average wind speed) are April and May (6mph).
The calmest month (with the lowest average wind speed) is October (4.8mph).
Average humidity in September
San Ysidro, CA
- Average humidity in September: 62%
The month with the highest relative humidity is May (68%).
The month with the lowest relative humidity is November (55%).
Average rainfall in September
San Ysidro, CA
- Average rainfall in September: 0.35"
The wettest month (with the highest rainfall) is February (1.5").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in September
San Ysidro, CA
- Average rainfall days in September: 4.5 days
The month with the highest number of rainy days is March (7.5 days).
The month with the least rainy days is June (1.8 days).
Average daylight in September /
Average sunshine in September
San Ysidro, 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 6min).
- Average sunshine in September: 10h and 12min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).
Average sunshine days in September
San Ysidro, CA
- Average sunshine days in September: 24.3 days
The month with the most sunshine days is June (27.8 days).
The month with the least sunshine days is February (20.8 days).
Average UV index in September
San Ysidro, 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 Ysidro, CA
- Average cloud cover in September: 12
The months with the most cloud cover are March and December (Cloud cover 25).
The month with the least cloud cover is August (Cloud cover 8).
Average visibility in September
San Ysidro, 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).
