Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
With the onset of September, a modest change to a still warm 80.8°F (27.1°C) from August's 81.9°F (27.7°C) is noted in high-temperature. In the month of September, San Marcos witnesses a consistent average low-temperature of 63.3°F (17.4°C).Heat index
Throughout September, the heat index is computed to be 82.4°F (28°C). Uninterrupted exposure and activity might result in fatigue, potentially causing heat cramps.Data suggests that the heat index is set for environments in shade and with a light wind. The heat index might be elevated by 15 Fahrenheit (8 Celsius) degrees due to direct sun exposure.
Note: The heat index, also known as 'real feel' or 'felt air temperature', is an indicator that blends the effects of temperature and humidity to depict perceived warmth. Elements such as metabolic variations, pregnancy, and physical exertion can influence one's weather perception. 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 extremely significant for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it's vital to remain hydrated, particularly during prolonged physical activities.
Humidity
The average relative humidity in September in San Marcos, California, is 62%.Rainfall
In September, the rain falls for 2.7 days. Throughout September, 0.16" (4mm) of precipitation is accumulated. Throughout the year, there are 52.1 rainfall days, and 6.1" (155mm) of precipitation is accumulated.Daylight
In September, the average length of the day in San Marcos is 12h and 22min.On the first day of September in San Marcos, California, sunrise is at 6:23 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:42 am and sunset at 6:33 pm PDT.
Sunshine
The average sunshine in September in San Marcos, California, is 10.4h.UV index
June through September, with an average maximum UV index of 6, are months with the highest UV index in San Marcos. A UV Index estimate of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for the ordinary person.Note: In September, the maximum UV index of 6 transforms into these recommendations:
Dodge overexposure. Fair-skinned people can get singed in less than 20 minutes. Limit direct sun exposure especially between 10 a.m. and 4 p.m., when UV radiation is at its peak. However, keep in mind that shade structures may not provide full sun protection. Boost your sun resistance with garments that are densely woven yet spacious.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in San Marcos?
What is the average humidity in September in San Marcos?
How many days does it rain in September in San Marcos?
How many hours of daylight does San Marcos have in September?
When is the sunrise / sunset in September in San Marcos?
How long on average sun shines in September in San Marcos?
What are the months with the highest UV index in San Marcos?
What is the UV index intensity in September in San Marcos?
Average temperature in September
San Marcos, CA
- Average high temperature in September: 80.8°F
The warmest month (with the highest average high temperature) is August (81.9°F).
The months with the lowest average high temperature are February and December (63.3°F).
- Average low temperature in September: 63.3°F
The month with the highest average low temperature is August (64.2°F).
The coldest month (with the lowest average low temperature) is February (48°F).
Average pressure in September
San Marcos, CA
- Average pressure in September: 29.88"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.87"Hg).
Average wind speed in September
San Marcos, CA
- Average wind speed in September: 4.5mph
The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest month (with the lowest average wind speed) is October (4.4mph).
Average humidity in September
San Marcos, CA
- Average humidity in September: 62%
The month with the highest relative humidity is May (70%).
The month with the lowest relative humidity is November (56%).
Average rainfall in September
San Marcos, CA
- Average rainfall in September: 0.16"
The wettest month (with the highest rainfall) is December (1.22").
The driest month (with the least rainfall) is June (0.08").
Average rainfall days in September
San Marcos, CA
- Average rainfall days in September: 2.7 days
The month with the highest number of rainy days is March (7.8 days).
The month with the least rainy days is June (1.2 days).
Average daylight in September /
Average sunshine in September
San Marcos, CA
- Average daylight in September: 12h and 2min
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 2min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 48min).
Average sunshine days in September
San Marcos, CA
- Average sunshine days in September: 25.3 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is February (20 days).
Average UV index in September
San Marcos, 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, March, November and December (UV index 4).
Average cloud cover in September
San Marcos, CA
- Average cloud cover in September: 10
The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 7).
Average visibility in September
San Marcos, 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).
San Marcos, California, USA
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