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 snowfall in September
- Average snowfall 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
Clearlake records a slight change with September's average high-temperatures adjusting to a warm 85.1°F (29.5°C) from August's 90.1°F (32.3°C). During September, Clearlake detects a significant contrast from its daytime temperatures, with nights averaging at a refreshing 55.8°F (13.2°C).Heat index
The heat index for September is estimated at a hot 86°F (30°C). Prolonged activity during exposure might result in a state of fatigue and cause heat cramps.Understand that the heat index values take into account shaded locations and mild winds. Exposure to the direct sun might augment heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', quantifies the warmth felt when relative humidity is considered. Additional factors encompassing metabolic differences, the level of physical activity, and clothing can impact the individual's perception of temperature. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are of high significance for children. Children usually face more risks than adults as their ability to sweat is less. Additionally, their larger skin surface in relation to their petite bodies and higher heat output due to their activities increases their vulnerability.
Humidity
In Clearlake, the average relative humidity in September is 45%.Rainfall
In Clearlake, California, during September, the rain falls for 2.1 days and regularly aggregates up to 0.08" (2mm) of precipitation. Throughout the year, there are 79.8 rainfall days, and 17.44" (443mm) of precipitation is accumulated.Snowfall
In Clearlake, snow does not fall in April through October.Daylight
The average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:40 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:54 pm PDT.
Sunshine
The average sunshine in September is 11.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for average individuals.Note: In September, the UV index of 5 transforms into the following advice:
Undertake precautions - Obligation exists to protect against skin and eye damage. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is it hot during September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow in Clearlake?
What is the average length of the day in September in Clearlake?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Clearlake, CA
- Average high temperature in September: 85.1°F
The warmest month (with the highest average high temperature) is July (91.2°F).
The month with the lowest average high temperature is December (52.7°F).
- Average low temperature in September: 55.8°F
The month with the highest average low temperature is July (58.8°F).
The coldest month (with the lowest average low temperature) is December (38.1°F).
Average pressure in September
Clearlake, CA
- Average pressure in September: 29.92"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June and August (29.91"Hg).
Average wind speed in September
Clearlake, CA
- Average wind speed in September: 4.6mph
The windiest month (with the highest average wind speed) is April (5.7mph).
The calmest month (with the lowest average wind speed) is November (4.3mph).
Average humidity in September
Clearlake, CA
- Average humidity in September: 45%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is July (44%).
Average rainfall in September
Clearlake, CA
- Average rainfall in September: 0.08"
The wettest month (with the highest rainfall) is February (3.7").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Clearlake, CA
- Average rainfall days in September: 2.1 days
The month with the highest number of rainy days is March (13.9 days).
The months with the least rainy days are July and August (1.1 days).
Average snowfall in September
Clearlake, CA
- Average snowfall in September: 0"
The month with the highest snowfall is February (0.51").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Clearlake, CA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (0.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Clearlake, CA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 11h and 1min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).
Average sunshine days in September
Clearlake, CA
- Average sunshine days in September: 27.1 days
The month with the most sunshine days is July (29.4 days).
The month with the least sunshine days is March (15.8 days).
Average UV index in September
Clearlake, CA
- Average UV index in September: 5
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are November and December (UV index 2).
Average cloud cover in September
Clearlake, CA
- Average cloud cover in September: 9
The month with the most cloud cover is March (Cloud cover 43).
The month with the least cloud cover is July (Cloud cover 4).
Average visibility in September
Clearlake, 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).
Clearlake, California, USA
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