September weather forecastGuerneville, CA
September
Weather in September
September, the first month of the autumn in Guerneville, is also a moderately hot month, with an average temperature ranging between max 79.9°F (26.6°C) and min 53.4°F (11.9°C).Temperature
The advent of September sees the average high-temperature at a still moderately hot 79.9°F (26.6°C), subtly shifted from August's 81°F (27.2°C). Despite drastic daily temperature oscillations, Guerneville cools down to an average low-temperature of 53.4°F (11.9°C) in September.Humidity
The least humid month in Guerneville, California, is September, with an average relative humidity of 62%.Rainfall
In September, the rain falls for 1.9 days. Throughout September, 0.08" (2mm) of precipitation is accumulated. In Guerneville, California, during the entire year, the rain falls for 60.1 days and collects up to 12.87" (327mm) of precipitation.Daylight
In Guerneville, the average length of the day in September is 12h and 25min.On the first day of September in Guerneville, sunrise is at 6:42 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:55 pm PDT.
Sunshine
In Guerneville, the average sunshine in September is 10.8h.UV index
In Guerneville, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: In September, the maximum UV index of 5 suggests these recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Guerneville, CA
- Average high temperature in September: 79.9°F
The warmest month (with the highest average high temperature) is August (81°F).
The month with the lowest average high temperature is December (56.3°F).
- Average low temperature in September: 53.4°F
The months with the highest average low temperature are August and September (53.4°F).
The coldest month (with the lowest average low temperature) is December (41.4°F).
Average pressure in September
Guerneville, 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
Guerneville, CA
- Average wind speed in September: 5.3mph
The windiest month (with the highest average wind speed) is May (7.2mph).
The calmest month (with the lowest average wind speed) is November (5mph).
Average humidity in September
Guerneville, CA
- Average humidity in September: 62%
The month with the highest relative humidity is March (77%).
The month with the lowest relative humidity is September (62%).
Average rainfall in September
Guerneville, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (3.27").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Guerneville, CA
- Average rainfall days in September: 1.9 days
The month with the highest number of rainy days is March (10.3 days).
The month with the least rainy days is August (0.9 days).
Average daylight in September /
Average sunshine in September
Guerneville, CA
- Average daylight in September: 12h and 24min
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 30min).
- Average sunshine in September: 10h and 48min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).
Average sunshine days in September
Guerneville, CA
- Average sunshine days in September: 27.9 days
The month with the most sunshine days is July (28.9 days).
The month with the least sunshine days is February (19.9 days).
Average UV index in September
Guerneville, CA
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Guerneville, CA
- Average cloud cover in September: 12
The month with the most cloud cover is March (Cloud cover 42).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in September
Guerneville, 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).
