September weather forecastLafayette, CA
September
Weather in September
The first month of the autumn, September, is still a warm month in Lafayette, California, with an average temperature fluctuating between 79.5°F (26.4°C) and 56.8°F (13.8°C).Temperature
Lafayette transitions into September recording an average high-temperature of a still warm 79.5°F (26.4°C), closely aligning with the preceding month's temperature. Throughout September, Lafayette notes a dramatic plunge from the daily high to an average low-temperature of 56.8°F (13.8°C).Humidity
In Lafayette, the average relative humidity in September is 61%.Rainfall
In Lafayette, in September, it is raining for 2.8 days, with typically 0.12" (3mm) of accumulated precipitation. Throughout the year, there are 74.4 rainfall days, and 12.6" (320mm) of precipitation is accumulated.Daylight
The average length of the day in September in Lafayette is 12h and 25min.On the first day of September, sunrise is at 6:39 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:52 pm PDT.
Sunshine
In September, the average sunshine is 11.1h.UV index
In Lafayette, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from unprotected exposure to Sun's UV rays for average individuals.Note: In September, the maximum UV index of 5 suggests this advice:
Take necessary precautions - Protection from skin and eye injury is mandatory. It's recommended to limit sun exposure when its radiation is at its peak during midday. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Lafayette, CA
- Average high temperature in September: 79.5°F
The warmest month (with the highest average high temperature) is July (80.1°F).
The month with the lowest average high temperature is December (55.2°F).
- Average low temperature in September: 56.8°F
The months with the highest average low temperature are August and September (56.8°F).
The coldest month (with the lowest average low temperature) is January (43.3°F).
Average pressure in September
Lafayette, 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, August and September (29.92"Hg).
Average wind speed in September
Lafayette, CA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is May (7.2mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).
Average humidity in September
Lafayette, CA
- Average humidity in September: 61%
The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is October (60%).
Average rainfall in September
Lafayette, CA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is February (2.6").
The driest months (with the least rainfall) are July and August (0.04").
Average rainfall days in September
Lafayette, CA
- Average rainfall days in September: 2.8 days
The month with the highest number of rainy days is March (13.1 days).
The month with the least rainy days is August (0.8 days).
Average daylight in September /
Average sunshine in September
Lafayette, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 11h and 6min
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 48min).
Average sunshine days in September
Lafayette, CA
- Average sunshine days in September: 25.9 days
The month with the most sunshine days is August (27.8 days).
The month with the least sunshine days is March (16.3 days).
Average UV index in September
Lafayette, CA
- Average UV index in September: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 3).
Average cloud cover in September
Lafayette, CA
- Average cloud cover in September: 11
The month with the most cloud cover is March (Cloud cover 36).
The month with the least cloud cover is July (Cloud cover 8).
Average visibility in September
Lafayette, 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).
