September weather forecast
San Geronimo, CA

Share

Weather in September

September, the first month of the autumn in San Geronimo, is still a pleasant month, with an average temperature fluctuating between 70.9°F (21.6°C) and 56.3°F (13.5°C).

Temperature

September temperatures tend to peak at an average high of 70.9°F (21.6°C) and dip to a low of 56.3°F (13.5°C).

Humidity

In San Geronimo, the average relative humidity in September is 73%.

Rainfall

In San Geronimo, California, during September, the rain falls for 3.4 days and regularly aggregates up to 0.12" (3mm) of precipitation. In San Geronimo, during the entire year, the rain falls for 80.3 days and collects up to 15.98" (406mm) of precipitation.

Snowfall

In San Geronimo, snow does not fall in January through November.

Daylight

In September, the average length of the day is 12h and 25min.
On the first day of the month, sunrise is at 6:41 am and sunset at 7:39 pm. On the last day of September, in San Geronimo, sunrise is at 7:06 am and sunset at 6:54 pm PDT.

Sunshine

The average sunshine in September in San Geronimo is 10.5h.

UV index

The months with the highest UV index in San Geronimo are June through September, with an average maximum UV index of 5. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: In September, a daily maximum UV index of 5 leads to the following instructions:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.

Frequently asked questions

What is the warmest month in San Geronimo?

In San Geronimo, September is the month with the highest recorded average temperatures, measuring a high of 70.9°F (21.6°C) and a low of 56.3°F (13.5°C).

What is the average September temperature in San Geronimo?

The high-temperature in San Geronimo, California, during September is 70.9°F (21.6°C) and the low-temperature is 56.3°F (13.5°C).

What is the average humidity in September in San Geronimo?

In September, the average relative humidity in San Geronimo, California, is 73%.

How much does it rain in San Geronimo in September?

In San Geronimo, California, in September, it is raining for 3.4 days, with typically 0.12" (3mm) of accumulated precipitation.

When it does not snow in San Geronimo?

In San Geronimo, snow does not fall in January through November.

What is the average length of the day in September in San Geronimo?

In San Geronimo, the average day length in September is 12h and 25min.

When is the sunrise / sunset in September in San Geronimo?

In September, on the first day of the month, sunrise is at 6:41 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:54 pm PDT.

How long on average sun shines in September in San Geronimo?

In San Geronimo, the average sunshine duration in September is 10.5h.

What is the month with the highest UV index in San Geronimo?

June through September, with an average maximum UV index of 5, are months with the highest UV index.

How high is the UV index in September in San Geronimo?

In San Geronimo, California, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium health risk from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
San Geronimo, CA

Average temperature in September - San Geronimo, CA
  • Average high temperature in September: 70.9°F

The warmest month (with the highest average high temperature) is September (70.9°F).
The month with the lowest average high temperature is December (55.2°F).

  • Average low temperature in September: 56.3°F

The month with the highest average low temperature is September (56.3°F).
The coldest month (with the lowest average low temperature) is December (46°F).

Average pressure in September
San Geronimo, CA

Average pressure in September - San Geronimo, CA
  • Average pressure in September: 29.92"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.92"Hg).

Average wind speed in September
San Geronimo, CA

Average wind speed in September - San Geronimo, CA
  • Average wind speed in September: 6.3mph

The windiest months (with the highest average wind speed) are April and May (8.3mph).
The calmest month (with the lowest average wind speed) is November (5.9mph).

Average humidity in September
San Geronimo, CA

Average humidity in September - San Geronimo, CA
  • Average humidity in September: 73%

The month with the highest relative humidity is August (78%).
The month with the lowest relative humidity is October (69%).

Average rainfall in September
San Geronimo, CA

Average rainfall in September - San Geronimo, CA
  • Average rainfall in September: 0.12"

The wettest month (with the highest rainfall) is February (3.43").
The driest months (with the least rainfall) are July and August (0.08").

Average rainfall days in September
San Geronimo, CA

Average rainfall days in September - San Geronimo, CA
  • Average rainfall days in September: 3.4 days

The month with the highest number of rainy days is March (12.8 days).
The month with the least rainy days is July (2.3 days).

Average snowfall days in September
San Geronimo, CA

Average snowfall days in September - San Geronimo, CA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is December (0.1 days).
The months with the least snowfall days are January, February, March, April, May, June, July, August, September, October and November (0 days).

Average daylight in September /
Average sunshine in September
San Geronimo, CA

Average daylight in September / Average sunshine in September - San Geronimo, CA
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).

  • Average sunshine in September: 10h and 3min

The month with the most sunshine is July (Average sunshine: 11h and 12min).
The month with the least sunshine is December (Average sunshine: 5h and 36min).

Average sunshine days in September
San Geronimo, CA

Average sunshine days in September - San Geronimo, CA
  • Average sunshine days in September: 24.1 days

The months with the most sunshine days are June and July (24.8 days).
The month with the least sunshine days is March (16.6 days).

Average UV index in September
San Geronimo, CA

Average UV index in September - San Geronimo, CA
  • Average UV index in September: 5

The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February, November and December (UV index 3).

Average cloud cover in September
San Geronimo, CA

Average cloud cover in September - San Geronimo, CA
  • Average cloud cover in September: 19

The month with the most cloud cover is March (Cloud cover 39).
The month with the least cloud cover is September (Cloud cover 19).

Average visibility in September
San Geronimo, CA

Average visibility in September - San Geronimo, 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 Geronimo, California, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location