Avg High
San Diego in September
Verdict
In San Diego, September has a distinct autumn feel. As the season moves along, conditions remain fairly consistent. You can usually expect a warm month that feels reliable day to day. The atmosphere is generally sunny and dry, perfect for uninterrupted outdoor plans.
It suits travellers who want straightforward weather for sightseeing and day trips. Most days are straightforward, and small timing choices matter more than big plan changes.
Avg Low
Rain
Daylight
12h
What to expect
- Daytime feel - Summer-like warmth with evenings that feel distinctly cooler. It can feel warmer than expected in the sun.
- Rain pattern - Mostly dry. Rain is usually intermittent rather than relentless. Rain is the exception rather than the rule.
- Sun & UV - High UV at midday. Cloud cover doesn't always mean low UV, so still protect your skin. Shade breaks feel genuinely worthwhile.
- Exposure - Often breezy, and gusts can catch you in exposed spots. A light outer layer helps when you’re in the shade.
September in context
How it compares to the rest of the year in San Diego.
Hottest (avg)
#2 / 12
Wettest (avg)
#9 / 12
Daylight Hours
#6 / 12
Windiest (avg)
#8 / 12
Highest UV
#6 / 12
Most Humid
#3 / 12
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight
- 12.4 hours
- UV index (max)
- 8
- Typical sun hours
- 05:32 – 17:53
Rain & Snow
- Total
-
- Rainy days
- 1
- Cloud cover
- 29%
- Snowfall
-
Humidity & Wind
- Humidity (avg)
- 78%
- Wind (avg)
-
- Wind (max gusts)
-
Frequently asked questions
Is September a good time to visit San Diego?
Typical September days in San Diego reach highs of 25°C (77°F) with nights around 18°C (64°F). It usually feels warm by day and mild after dark. Overall, September sits in the middle of the San Diego climate range.
What are temperatures like in September?
Daytime temperatures in September typically peak near 25°C (77°F), while nights drop to around 18°C (64°F). Expect warm afternoons and mild evenings.
How much does it rain in September?
Rainfall in September averages 6 mm (0.24 in) across roughly 1 days. Overall it is a mostly dry time of year, so showers are usually brief rather than all-day downpours.
How many hours of daylight are there in September?
You can expect about 12 hours of daylight in September. Sunrise is typically around 05:32 and sunset near 17:53. Daylight is fairly typical, with enough time for sightseeing.
How strong is the sun in September?
UV levels are often high (around 8). Regular sunscreen and a hat are recommended.
Is it windy in September?
In September, average wind speeds are around 9 km/h (6 mph), with gusts on the windiest days reaching about 37 km/h (23 mph). On the ground, it is a gentle to moderate breeze is common, but stronger winds are not frequent.