September weather forecast
Rancho Bernardo, CA

Share

Weather in September

September, the first month of the autumn in Rancho Bernardo, is still a warm month, with temperature in the range of an average low of 63.1°F (17.3°C) and an average high of 82.6°F (28.1°C).

Temperature

Transitioning from August to September, Rancho Bernardo observes an average high-temperature of a still moderately hot 82.6°F (28.1°C), differing subtly from the previous month. The low-temperature average for Rancho Bernardo during September stands at a refreshing 63.1°F (17.3°C).

Heat index

During September, the heat index is calculated to be a hot 86°F (30°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Know that the heat index computations account for shaded terrains and slight winds. Direct sunlight might cause an increase of up to 15 Fahrenheit (8 Celsius) degrees in the heat index.
Note: The heat index, also known as 'real feel' or 'apparent temperature', provides an understanding of perceived warmth by combining temperature and relative humidity. This effect is personal, influenced by the individual's physical activity and heat sensitivity, shaped by factors including wind, attire, and metabolic variations. You should know that direct sun exposure can heighten weather effects, potentially elevating the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are largely significant for babies and toddlers. Young ones are generally at greater risk than adults due to their limited sweating ability. In addition, their large skin surface relative to their small bodies and higher heat production from their activities add to their vulnerability.

Humidity

In Rancho Bernardo, the average relative humidity in September is 60%.

Rainfall

In September, in Rancho Bernardo, the rain falls for 3.8 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. Throughout the year, in Rancho Bernardo, there are 54.7 rainfall days, and 8.15" (207mm) of precipitation is accumulated.

Daylight

In September, the average length of the day is 12h and 22min.
On the first day of the month, sunrise is at 6:23 am and sunset at 7:12 pm. On the last day of September, sunrise is at 6:42 am and sunset at 6:33 pm PDT.

Sunshine

The average sunshine in September is 10.3h.

UV index

June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: In September, the maximum UV index of 6 transforms into these recommendations:
Deflect overexposure. Sun protection is a necessity. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
[Resources]

Frequently asked questions

How hot is September in Rancho Bernardo?

An average high-temperature, in September, in Rancho Bernardo, is 82.6°F (28.1°C) and the average low-temperature is 63.1°F (17.3°C). The average heat index (a.k.a. 'apparent temperature', 'real feel'), which calculates the temperature value influenced by the moisture in the air, in September is calculated to be 86°F (30°C).

What is the average humidity in September in Rancho Bernardo?

In Rancho Bernardo, the average relative humidity in September is 60%.

How much does it rain in Rancho Bernardo in September?

In Rancho Bernardo, California, in September, it is raining for 3.8 days, with typically 0.31" (8mm) of accumulated precipitation.

What is the average length of the day in September in Rancho Bernardo?

In September, the average day length in Rancho Bernardo is 12h and 22min.

What time are sunrise and sunset in September in Rancho Bernardo?

On the first day of September in Rancho Bernardo, California, sunrise is at 6:23 am and sunset at 7:12 pm. On the last day of the month, sunrise is at 6:42 am and sunset at 6:33 pm PDT.

How many hours of sunshine does Rancho Bernardo have in September?

In September, the average sunshine duration in Rancho Bernardo, California, is 10.3h.

When is the highest UV index in Rancho Bernardo?

June through September, with an average maximum UV index of 6, are months with the highest UV index in Rancho Bernardo, California.

How high is the UV index in September in Rancho Bernardo?

The average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Rancho Bernardo, CA

Average temperature in September - Rancho Bernardo, CA
  • Average high temperature in September: 82.6°F

The warmest month (with the highest average high temperature) is August (84.2°F).
The month with the lowest average high temperature is December (63.9°F).

  • Average low temperature in September: 63.1°F

The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is February (47.1°F).

[Resources]

Average pressure in September
Rancho Bernardo, CA

Average pressure in September - Rancho Bernardo, CA
  • Average pressure in September: 29.87"Hg

The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are June and September (29.87"Hg).

[Resources]

Average wind speed in September
Rancho Bernardo, CA

Average wind speed in September - Rancho Bernardo, CA
  • Average wind speed in September: 4.3mph

The windiest month (with the highest average wind speed) is April (5.5mph).
The calmest months (with the lowest average wind speed) are September and October (4.3mph).

[Resources]

Average humidity in September
Rancho Bernardo, CA

Average humidity in September - Rancho Bernardo, CA
  • Average humidity in September: 60%

The month with the highest relative humidity is May (68%).
The month with the lowest relative humidity is November (54%).

[Resources]

Average rainfall in September
Rancho Bernardo, CA

Average rainfall in September - Rancho Bernardo, CA
  • Average rainfall in September: 0.31"

The wettest month (with the highest rainfall) is February (1.61").
The driest month (with the least rainfall) is June (0.08").

[Resources]

Average rainfall days in September
Rancho Bernardo, CA

Average rainfall days in September - Rancho Bernardo, CA
  • Average rainfall days in September: 3.8 days

The month with the highest number of rainy days is March (7.2 days).
The month with the least rainy days is June (1.6 days).

[Resources]

Average daylight in September /
Average sunshine in September
Rancho Bernardo, CA

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

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

  • Average sunshine in September: 10h and 2min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 6h and 42min).

[Resources]

Average sunshine days in September
Rancho Bernardo, CA

Average sunshine days in September - Rancho Bernardo, CA
  • Average sunshine days in September: 23.9 days

The month with the most sunshine days is June (27 days).
The month with the least sunshine days is February (21.2 days).

[Resources]

Average UV index in September
Rancho Bernardo, CA

Average UV index in September - Rancho Bernardo, CA
  • Average UV index in September: 6

The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 4).

[Resources]

Average cloud cover in September
Rancho Bernardo, CA

Average cloud cover in September - Rancho Bernardo, CA
  • Average cloud cover in September: 10

The month with the most cloud cover is March (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 7).

[Resources]

Average visibility in September
Rancho Bernardo, CA

Average visibility in September - Rancho Bernardo, 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).

[Resources]

Rancho Bernardo, California, USA

Weather forecast for your location

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