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
Transitioning from August to September, San Francisco observes an average high-temperature of a still warm 26.3°C (79.3°F), differing subtly from the previous month. An average minimum temperature of 19.2°C (66.6°F) marks the month of September.Humidity
The average relative humidity in September in San Francisco is 87%.Rainfall
In San Francisco, in September, during 29.4 rainfall days, 288mm (11.34") of precipitation is typically accumulated. In San Francisco, during the entire year, the rain falls for 272 days and collects up to 2217mm (87.28") of precipitation.Daylight
In San Francisco, the average length of the day in September is 12h and 11min.On the first day of September in San Francisco, sunrise is at 05:27 and sunset at 17:45. On the last day of the month, sunrise is at 05:24 and sunset at 17:27 CST.
Sunshine
In San Francisco, Costa Rica, the average sunshine in September is 7.6h.UV index
January through April, June, July, September, October and December, with an average maximum UV index of 6, are months with the highest UV index in San Francisco. A UV Index value of 6 to 7 symbolizes a high health risk from unsafe exposure to UV radiation for the ordinary person.Note: In September, the maximum UV index of 6 suggests this advice:
Resist overexposure. Safeguarding from solar damage is indispensable. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is at its strongest, and remember that parasols or canopies do not offer full protection. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses.
Frequently asked questions
What is the temperature in September in San Francisco?
What is the average humidity in September in San Francisco?
How many days does it rain in September in San Francisco?
What is the average length of the day in September in San Francisco?
When are sunrise and sunset in September in San Francisco?
How long on average sun shines in September in San Francisco?
When is the highest UV index in San Francisco?
What is the UV index reading in September in San Francisco?
Average temperature in September
San Francisco, Costa Rica
- Average high temperature in September: 26.3°C
The warmest months (with the highest average high temperature) are March and April (29.7°C).
The month with the lowest average high temperature is October (25.4°C).
- Average low temperature in September: 19.2°C
The month with the highest average low temperature is May (19.8°C).
The coldest month (with the lowest average low temperature) is January (16.8°C).
Average pressure in September
San Francisco, Costa Rica
- Average pressure in September: 1011mbar
The month with the highest atmospheric pressure is January (1012.1mbar).
The month with the lowest atmospheric pressure is October (1010.7mbar).
Average wind speed in September
San Francisco, Costa Rica
- Average wind speed in September: 3.8km/h
The windiest month (with the highest average wind speed) is February (10.6km/h).
The calmest month (with the lowest average wind speed) is September (3.8km/h).
Average humidity in September
San Francisco, Costa Rica
- Average humidity in September: 87%
The month with the highest relative humidity is October (89%).
The month with the lowest relative humidity is March (70%).
Average rainfall in September
San Francisco, Costa Rica
- Average rainfall in September: 288mm
The wettest month (with the highest rainfall) is October (396mm).
The driest month (with the least rainfall) is February (17mm).
Average rainfall days in September
San Francisco, Costa Rica
- Average rainfall days in September: 29.4 days
The month with the highest number of rainy days is October (30.2 days).
The month with the least rainy days is February (10.3 days).
Average daylight in September /
Average sunshine in September
San Francisco, Costa Rica
- Average daylight in September: 12h and 1min
The month with the longest days is June (Average daylight: 12h and 42min).
The month with the shortest days is December (Average daylight: 11h and 36min).
- Average sunshine in September: 7h and 4min
The month with the most sunshine is March (Average sunshine: 9h and 24min).
The month with the least sunshine is October (Average sunshine: 7h and 0min).
Average sunshine days in September
San Francisco, Costa Rica
- Average sunshine days in September: 0.5 days
The month with the most sunshine days is January (16.7 days).
The month with the least sunshine days is September (0.5 days).
Average UV index in September
San Francisco, Costa Rica
- Average UV index in September: 6
The months with the highest UV index are January, February, March, April, June, July, September, October and December (UV index 6).
The months with the lowest UV index are May, August and November (UV index 5).
Average cloud cover in September
San Francisco, Costa Rica
- Average cloud cover in September: 50
The month with the most cloud cover is October (Cloud cover 54).
The month with the least cloud cover is February (Cloud cover 19).
Average visibility in September
San Francisco, Costa Rica
- Average visibility in September: 7km
The months with the highest visibility are February and March (10km).
The months with the lowest visibility are August, September, October and November (7km).
San Francisco, Costa Rica
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