Weather

San Diego Weather in September

With average highs of 67°F, lows of 56°F, and 0.78 inches of rainfall across five days, September weather in San Diego offers a pleasant climate for outdoor activities, beach outings, and vibrant city events.

by Mac Douglass

Updated March 01, 2025

What Is the Weather Like in San Diego in September?

September in San Diego continues the trend of warm, sunny days with cooler evenings. Average highs reach 67°F (19°C), while lows drop to 56°F (13°C). Rainfall slightly increases compared to the summer months, averaging 0.78 inches over five days.

Ocean temperatures remain warm, making it one of the last great months for swimming, surfing, and other water activities.

Average September Weather in San Diego

San Diego's September weather features warm highs around 67°F and cooler lows near 56°F, with light rainfall, making it ideal for seasonal events and outdoor activities. Data from WeatherSpark.

Daytime Temperatures: Highs average 67°F, offering comfortably warm days.
Nighttime Temperatures: Lows average 56°F, perfect for cool evening strolls.
Rainfall: September experiences 0.78 inches of rainfall across five days.
Ocean Temperatures: Coastal waters remain inviting for beachgoers and surfers.

September San Diego Weather Compared to Other Months

Month	Average High (°F)	Average Low (°F)	Days with Precipitation	Hours of Sunshine	Average Precipitation (in)
January	65	48	6	217	1.53
February	76	65	1	255	0.15
March	73	61	3	234	0.57
April	69	54	4	236	1.01
May	76	67	0	277	0.02
June	75	65	0	293	0.03
July	71	62	1	253	0.07
August	69	59	2	261	0.12
September	67	56	5	242	0.78
October	66	53	7	262	1.81
November	65	51	7	212	2.27
December	65	49	7	216	1.98

San Diego’s weather in September is slightly cooler and wetter than August, but it remains ideal for outdoor adventures.

Compared to October, which averages highs of 66°F and lows of 53°F, September provides warmer ocean temperatures and more summer-like conditions.

Things to Do in San Diego in September

San Diego’s September weather perfectly complements a variety of exciting events and activities.

San Diego Bayfair (September 13-15): Watch high-speed powerboat racing and enjoy family-friendly activities at Mission Bay.
San Diego Restaurant Week (September 22-29): Savor culinary delights from over 100 restaurants across 30 neighborhoods.
MCAS Miramar Air Show (September 27-29): Experience thrilling military and civilian aerobatic performances.
Adams Avenue Street Fair (September 21-22): Attend SoCal's largest free two-day music festival.
SeaWorld Howl-O-Scream (September 26 - November 2): Kick off spooky season with terrifying nighttime attractions.

Why Visit San Diego in September?

San Diego’s September weather provides warm days, cool evenings, and slightly higher rainfall, offering a smooth transition from summer to fall. Highlights include:

Extended beach season with warm ocean temperatures.
Unique seasonal events like the Julian Grape Stomp Festa and FilmOut San Diego LGBT Film Festival.
Opportunities for family fun at events like the Poway Rodeo and San Diego Bayfair.

Plan Your Trip Around the September Weather in San Diego, California

September in San Diego blends the best of summer and fall, offering a mild climate, vibrant festivals, and endless activities for visitors of all ages. Whether you're exploring the city's culinary scene, enjoying cultural celebrations, or relaxing by the beach, San Diego in September is sure to impress.