September weather forecast
Yosemite National Park, CA

September witnesses a moderate decline in temperatures in Yosemite National Park, paving the way for the autumn season. Receiving an average of 0.7" (18mm) of rainfall, the weather conditions remain relatively dry. With daylight reducing to 12.4 hours and 10 hours of sunshine, the environment vibrantly transforms. The cool weather complements the changing foliage; leaves turn into variegated shades of yellow, gold, and red. The park's ground is strewn with fall leaves, creating a colorful carpet that enchants every visitor.

Temperature

As September commences, the average high-temperature subtly reduces, transitioning from a hot 89.4°F (31.9°C) in August to a warm 83.5°F (28.6°C). Throughout September nights, Yosemite National Park reports a steady thermal contrast from the day, with an average low-temperature of 46.8°F (8.2°C).

Rainfall

In Yosemite National Park, during September, the rain falls for 2 days and regularly aggregates up to 0.67" (17mm) of precipitation. In Yosemite National Park, during the entire year, the rain falls for 65 days and collects up to 36.26" (921mm) of precipitation.

Snowfall

June through September are months without snowfall.

Daylight

In September, the average length of the day is 12h and 25min.
On the first day of September, sunrise is at 6:28 am and sunset at 7:26 pm. On the last day of the month, sunrise is at 6:53 am and sunset at 6:42 pm PDT.

Sunshine

In Yosemite National Park, the average sunshine in September is 10h.

UV index

The average daily maximum UV index in September is 8. A UV Index reading of 8 to 10 represents a very high threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In September, a daily UV index of 8 turns into the following recommendations:
Take the necessary steps to protect yourself; unprotected skin and eyes are vulnerable to damage. Stay out of direct sunlight between 10 a.m. and 4 p.m., when UV radiation is most intense, and remember that not all shade structures provide complete protection. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear.