September weather forecast
Upper Lake, CA

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Weather in September

September, the first month of the autumn in Upper Lake, is also a moderately hot month, with an average temperature fluctuating between 84.2°F (29°C) and 54.1°F (12.3°C).

Temperature

September registers an average high-temperature of a moderately hot 84.2°F (29°C), slightly varied from August's 89.1°F (31.7°C). A notable decrease from the day's highest temperature marks September, culminating in an average low of 54.1°F (12.3°C).

Heat index

September's mean heat index is estimated at 84.2°F (29°C). Exhaustion might be the outcome of enduring exposure and continuous activity, with a risk of heat cramps.
Regarding the heat index, one should be aware it's determined by shaded settings and mild winds. Heat index values might soar by up to 15 Fahrenheit (8 Celsius) degrees with exposure to direct sunshine.
Note: The heat index, also known as 'felt air temperature' or 'feels like', marries air temperature and humidity to produce a value illustrating perceived warmth. The effect is experienced differently by individuals, hinging on unique characteristics such as body mass, stature, and level of activity. Exposure to direct sun rays can influence the heat you feel, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Juveniles often do not understand the need to recuperate and rehydrate. Thirst is a delayed symptom of dehydration - hence, it is vital to maintain hydration, particularly during ongoing physical activities.

Humidity

The average relative humidity in September is 48%.

Rainfall

In September, the rain falls for 2.5 days. Throughout September, 0.16" (4mm) of precipitation is accumulated. Throughout the year, there are 92 rainfall days, and 21.02" (534mm) of precipitation is accumulated.

Snowfall

April through October are months without snowfall.

Daylight

The average length of the day in September is 12h and 26min.
On the first day of September in Upper Lake, sunrise is at 6:41 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 Upper Lake, the average sunshine in September is 11h.

UV index

In Upper Lake, California, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for ordinary individuals.
Note: The average daily UV index of 5 in September transforms into the following instructions:
Ensure safety - Sun damage prevention is strongly urged. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage.
Updated: Jun 22, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How hot is September?

During September, Upper Lake experiences an average high-temperature of 84.2°F (29°C) and a low-temperature of 54.1°F (12.3°C). The average heat index (a.k.a. 'feels like', 'real feel'), which combines relative humidity and air temperature, in September is estimated at 84.2°F (29°C).

What is the average humidity in September?

In September, the average relative humidity is 48%.

How many days does it rain in September?

In Upper Lake, in September, during 2.5 rainfall days, 0.16" (4mm) of precipitation is typically accumulated.

When it does not snow?

In Upper Lake, snow does not fall in April through October.

What is the average length of the day in September?

In Upper Lake, California, the average day length in September is 12h and 26min.

When are sunrise and sunset in September?

On the first day of September, sunrise is at 6:41 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.

How long on average sun shines in September?

The average sunshine duration in September is 11h.

What is the UV index intensity in September?

In Upper Lake, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium hazard to health from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Upper Lake, CA

Average temperature in September - Upper Lake, CA
  • Average high temperature in September: 84.2°F

The warmest month (with the highest average high temperature) is July (89.6°F).
The month with the lowest average high temperature is December (52.3°F).

  • Average low temperature in September: 54.1°F

The month with the highest average low temperature is July (57.7°F).
The coldest month (with the lowest average low temperature) is December (37.2°F).

Average pressure in September
Upper Lake, CA

Average pressure in September - Upper Lake, 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
Upper Lake, CA

Average wind speed in September - Upper Lake, CA
  • Average wind speed in September: 4.3mph

The windiest month (with the highest average wind speed) is April (5.3mph).
The calmest month (with the lowest average wind speed) is November (4.1mph).

Average humidity in September
Upper Lake, CA

Average humidity in September - Upper Lake, CA
  • Average humidity in September: 48%

The month with the highest relative humidity is March (75%).
The month with the lowest relative humidity is July (47%).

Average rainfall in September
Upper Lake, CA

Average rainfall in September - Upper Lake, CA
  • Average rainfall in September: 0.16"

The wettest month (with the highest rainfall) is February (4.06").
The driest month (with the least rainfall) is July (0.04").

Average rainfall days in September
Upper Lake, CA

Average rainfall days in September - Upper Lake, CA
  • Average rainfall days in September: 2.5 days

The month with the highest number of rainy days is March (15.9 days).
The months with the least rainy days are July and August (1.3 days).

Average snowfall in September
Upper Lake, CA

Average snowfall in September - Upper Lake, CA
  • Average snowfall in September: 0"

The months with the highest snowfall are January and February (0.47").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in September
Upper Lake, CA

Average snowfall days in September - Upper Lake, 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
Upper Lake, CA

Average daylight in September / Average sunshine in September - Upper Lake, 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 0min

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
Upper Lake, CA

Average sunshine days in September - Upper Lake, CA
  • Average sunshine days in September: 26.7 days

The months with the most sunshine days are July and August (28.3 days).
The month with the least sunshine days is March (13.7 days).

Average UV index in September
Upper Lake, CA

Average UV index in September - Upper Lake, 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
Upper Lake, CA

Average cloud cover in September - Upper Lake, CA
  • Average cloud cover in September: 10

The month with the most cloud cover is March (Cloud cover 44).
The months with the least cloud cover are July and August (Cloud cover 5).

Average visibility in September
Upper Lake, CA

Average visibility in September - Upper Lake, CA
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are March and December (5mi).

Upper Lake, California, USA

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