The month in detail
What to expect in September
Autumn in San Diego is often underrated: 24°C, golden light and declining crowds. An interesting window. Rain is virtually absent (4% of days) — ideal for planning without a backup. A good balance between weather and crowds, even if July (9.2/10) remains theoretically better.
September ranks 3 out of 12 months in San Diego. Compared to August: −1.1h of sun per day.
This month's conditions
What it's like in September
UV index
7 · high
sunscreen and hat advised
Feels like
muggy at times
17°
Sea
22°C
pleasant for swimming
Daylight
12.2h of daylight
Air quality
good
AQI 32
Compare
Is September the right month?
The best month in San Diego is July (9.2/10), 0.4 pt higher than September.
Book
Plan your trip
Hotels at their lowest outside peak season, highest on comfortable months. Shoulder seasons offer a good price/climate compromise.
Stay
Hotels & rentals · San Diego
Expedia →
Activities
Tours, tickets, experiences
See ↓
Flights
Multi-airline comparator
Kiwi →
🎟️ Activities & tours · San Diego
GetYourGuide selection · free cancellation
Practical info
What you need to know before you go
Three angles: the country (language, currency, safety, budget), the year-round climate, and the specifics of a beach holiday.
Country · United States
🗣️LanguageEnglish
💶CurrencyUS Dollar ($)
🚗DrivingRight-hand
🛡️Safety ⓘVery safe · 1/5
💰Cost of living ⓘExpensive · 4/5
🌡️ Climate
🌍Climate typeTemperate oceanic
📈Climate trend ⓘStable
🔥Hottest monthAugust · 25°C
❄️Coolest monthJanuary · 17°C
🌧️Rainiest month ⓘMarch · 18%
🏖️ Beach holiday
📅Peak seasonJuin → Sept
🏖️Swell (Sept–Mar) ⓘModérée
Explore
Other destinations in September
If September doesn't convince you for this destination, compare with others.
Similar climate
Santa BarbaraUnited StatesLos AngelesUnited States
EssaouiraMorocco
El HierroSpain
SantoriniGreece
Location
Where is San Diego ?
Global position + regional geographic context.
🌍 World
🔍 Geographic context
United StatesTemperate oceanic climate with a 9.2 → 7.4 gap between best and worst month. 10 years of ERA5 data to choose by project.
32.72°N · 117.16°W
Questions
Frequently asked questions
What is the best time to visit San Diego?
July is the best month with 24.0°C highs, 18.0°C lows, 9.8h of sunshine and 1.0% rainy days. The months of July & August offer comparable conditions.
How many hours of sunshine does San Diego get in July?
San Diego averages 9.8 sunshine hours per day in July. It is the sunniest month with a climate score of 8.8/10.
What is the rainiest month in San Diego?
January is the most unfavourable month with January has the lowest climate score of the year and the lowest climate score of the year.
What are the temperatures at night in San Diego in July?
In July, overnight lows reach 18.0°C, while afternoon highs average 24.0°C.
Is San Diego good in winter?
In winter (December-February), San Diego scores 7.1/10 on average — Decent period conditions for cultural visits.. The best month overall remains July with a score of 8.8/10.
When should you avoid San Diego?
January is the most difficult month to visit San Diego, with January has the lowest climate score of the year. Climate conditions are at their lowest of the year during this period.
Can you swim in San Diego in September?
In September, the sea averages 22°C in San Diego: pleasant for swimming. Swimming is pleasant without a wetsuit.
Do you need sun protection in San Diego in September?
The average UV index reaches 7 in September in San Diego (high), with about 12.2h of daylight. Sunscreen and hat advised.