Verdict: Excellent month
San Diego Weather in September
September hits the sweet spot in San Diego — highs around 25°C (77°F), ideal for a full day on foot. Rain is a non-issue, with only ~1 wet day in an average year. Overall, September is one of the best months of the year to be in San Diego.
Average high
25°C / 77°F
Average low
18°C / 64°F
Rain days
~1
Precipitation
14 mm
What to pack for San Diego in September
- Summer clothes, plus one light layer for air-con and evenings
- Comfortable walking shoes — every guide on this site assumes you'll use them
September against the rest of the year
Warmest in San Diego: Aug (26°C / 79°F) · Coolest: Jan (17°C / 63°F) · Wettest: Mar (~10 rain days)
17°
8°
Jan
18°
8°
Feb
17°
10°
Mar
19°
12°
Apr
20°
14°
May
22°
16°
Jun
24°
18°
Jul
26°
19°
Aug
25°
18°
Sep
24°
15°
Oct
21°
11°
Nov
18°
9°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)